Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
techtalk:evo:carb02 [2020/08/25 07:55]
ixl2relax
techtalk:evo:carb02 [2024/01/02 21:51] (current)
hippysmack
Line 2: Line 2:
 ====== EVO: Carburetor, Intake Manifold & Exhaust ====== ====== EVO: Carburetor, Intake Manifold & Exhaust ======
  
 +\\
 +
 +The EVO Sportsters have used Keihin carburetors from 1986-2006. The CV design was used from 1988, with the 1989 models getting an upgraded version with an accelerator pump. Sportster models from 2007-later use fuel-injection.
 +
 +The following information is most relevant for 1989-2006 models, although many of the principles are applicable to other carbs and other years.
  
 \\ \\
  
-====== ​CV CARBURETOR DESIGN ======+====== ​CV40 CARBURETOR DESIGN ======
  
 **Design Info** **Design Info**
  
-From 1989-later, the carburetor installed on Sportsters was made by Keihin. ​It has a 40mm maximum venturi, but the design of the constant-velocity carb utilizes a vacuum-operated slide to vary the venturi opening to help maintain a good air velocity throughout the carbs operating range.+From 1989-later, the carburetor installed on Sportsters was made by Keihin. ​Known as the CV40, it has a 40mm maximum venturi, but the design of the constant-velocity carb utilizes a vacuum-operated slide to vary the venturi opening to help maintain a proper ​air velocity throughout the carbs operating range
 + 
 +The CV40 uses a gravity-fed fuel supply through a float controlled inlet valve to fill a fuel supply bowl, from which the internal jets obtain fuel. It also has an enrichment system, mislabeled a choke. This provides a pathway for fuel to bypass most of the carb operation and be supplied directly into the manifold, at the rear of the carb, for better starting. There are air passages to the fuel pathways to mix the air and fuel together. 
 + 
 +There are a number of parts that operate in combination to control the mixing of fuel & air into a combustible fuel mixture. The vacuum slide, needle, needle jet, emulsion tube, main jet, slow jet (with an emulsion tube), idle mixture screw, idle ports, tranfer ports and accelerator pump, all assist in this mixing operation over the range of operating conditions. 
 + 
 +The purpose of the carburetor is to atomize fuel into the incoming air such that a proper air-fuel-ratio (AFR) is achieved for varying conditions. The Slow Jet (AKA Pilot Jet) & Main Jet each use an emulsion tube with a fuel orifice & air holes. Each emulsion tube pulls fuel from the float bowl reserve and is fed air thru small air ports (called air jets) on the face of the carb (filter side). In each case, the emulsion tube produces an air/fuel mixture that is further mixed with the air flowing into the venturi (carburetor throat). 
 + 
 +The air flow is generally controlled by the Throttle Plate along with the vertically moving slide that essentially varies the venturi size to create a Constant Velocity of air (from which it gets it's name). By selecting various Slow and Main Jets, the AFR can be altered to produce a preferred ratio. Air flowing into the venturi creates a vacuum which pulls the air/fuel mixture from the emulsion tubes into the air stream.
  
-The CV40 uses gravity-fed fuel supply through a float controlled inlet valve to fill a fuel supply bowlfrom which the internal jets obtain fuel. It also has an enrichment system ​(mislabeled choke) that provides a pathway for fuel to bypass ​the carb and be supplied ​directly into the manifold ​for better starting.+To create ​proper idle operation, the Idle Port (on the engine side of the throttle plate) ​has a separate adjustable screw (Idle Mixture Screw) that allows some of the mixture from the Pilot Jet emulsion tube to be bled directly into the manifold, bypassing the throttle plate.
  
-There are a number of parts that operate in combination to control ​the mixing of fuel & air into a combustible fuel mixtureThe vacuum slide, needle, main jet, slow jet, idle mixture screw, idle ports, tranfer ports and accelerator pump, all assist ​in this mixing operation over the range of operating conditions.+As the throttle plate is opened, ​fuel is pulled from the Transfer PortsWith more throttlefuel is pulled thru the needle jet, in greater quantity as the tapered needle is lifted out of the needle jet opening by the vacuum-operated slide.
  
-The constant-velocity system provides a partial means of compensating for operation at different altitudes. In a fixed system, as altitude increases, the fuel mixture becomes richer due to the thinner air. But the CV system partially compensates for this fact because the vacuum-slide ​oparation ​is also affected by the thiner ​air, thereby supplying less fuel into the mix.+The constant-velocity system provides a partial means of compensating for operation at different altitudes. In a fixed system, as altitude increases, the fuel mixture becomes richer due to the thinner air. But the CV system partially compensates for this fact because the vacuum-slide ​operation ​is also affected by the thinner ​air, thereby supplying less fuel into the mix to match the reduced air density.
  
 The CV40 (1989-later) has an accelerator pump, controlled by a rod attached to the throttle cable cam, to provide additional fuel when the throttle is quickly opened for acceleration. It squirts raw fuel into the venturi throat to enhance the fuel mixture along with the quickly added air. The CV40 (1989-later) has an accelerator pump, controlled by a rod attached to the throttle cable cam, to provide additional fuel when the throttle is quickly opened for acceleration. It squirts raw fuel into the venturi throat to enhance the fuel mixture along with the quickly added air.
  
-The carb has been adjusted to control exhaust emissions. The idle mixture is set at the factory and the adjusting screw is capped because it is not to be adjusted except by factory technicians.+The stock carb has been adjusted to control exhaust emissions. The idle mixture is set at the factory and the adjusting screw is capped because it is not intended ​to be adjusted except by factory technicians. However, the cap can be removed and adjustments made as needed.
  
-Note from the service manual: Adjusting mixture setting by procedures other than specified in this section may be in violation of local regulations.+From the service manual ​(FYI): Adjusting mixture setting by procedures other than specified in this section may be in violation of local regulations.
  
 \\ \\
Line 33: Line 46:
 Even so, if done methodically,​ with careful attention to detail, most DIY riders do get their tune 'close enough'​ to match the modified air cleaner & exhaust upgrade (generally known as a Stage One upgrade) with just a handful of parts. Even so, if done methodically,​ with careful attention to detail, most DIY riders do get their tune 'close enough'​ to match the modified air cleaner & exhaust upgrade (generally known as a Stage One upgrade) with just a handful of parts.
  
-Over the years there have been many different approaches to tuning the CV carb - some of them simply distorting the tune to skew it's operation toward some (perceived) '​enhancement'​ of a specific part of the throttle operation curve. Unfortunately,​ when most of this advice is followed, the normal street rider is left with '​problem'​ areas in the overall throttle ​curve and they then use 'trial & error' with many other changes to address those 'tune created'​ problems. It doesn'​t take long to be confused and dissatisfied.+Over the years there have been many different approaches to tuning the CV carb - some of them simply distorting the tune to skew it's operation toward some (perceived) '​enhancement'​ of a specific part of the throttle operation curve. Unfortunately,​ when most of this advice is followed, the normal street rider is left with '​problem'​ areas in the overall throttle ​range and they then use 'trial & error' with many other changes to address those 'tuning ​created'​ problems. It doesn'​t take long to be confused and dissatisfied.
  
-With the collected results of many years of (reported) experimentation,​ some of the older suggestions have been found to be unacceptable for a good overall carb tune. Therefore, just because it was recommended in the past does not make it a good idea. This is especially true where permanent modifications (damage) are suggested for the stock carb parts. In the XLForum, there is quite a general consensus (although some still disagree) that a well tuned carb for the entire throttle ​curve, is one with NO permamently modified carb parts, but rather, that tune only uses a change in the needle and jets while carefully ​tuning the carb adjustments.+With the collected results of many years of (reported) experimentation,​ some of the older suggestions have been found to be unacceptable for a good overall carb tune. Therefore, just because it was recommended in the past does not make it a good idea. This is especially true where permanent modifications (damage) are suggested for the stock carb parts. In the XLForum, there is quite a general consensus (although some still disagree) that a well tuned carb for the entire throttle ​range, is one with NO permamently modified carb parts, but rather, that tuning ​only uses a change in the needle and jets while carefully ​making ​carb adjustments.
  
-Another ​issue created by the factory carb settings to meet EPA regs, is that the CV carb has often had off-idle carb farts with the factory tune, which flare up with stage 1 modifications. There have been a number of proposed '​solutions'​ to the carb fart problem (with some of those '​solutions'​ creating other issues).+An issue created by the factory carb settingsto meet EPA regs, is that the CV carb has often had off-idle ​(lean) ​carb farts with the factory tune, which increase after stage 1 modifications. There have been a number of proposed '​solutions'​ to the carb fart problem (with some of those '​solutions'​ creating other issues).
  
-Below you will find many collected suggestions that should get a Stage One, 1200cc Sportster properly tuned for a balance of performance and smooth, reliable, street operation. The same principles will apply to 883 models and also to somewhat-upgraded (1250/1275) engine sizes, but with only the necessary parts altered ​to meet the needs of the particular engine.+Below you will find many collected suggestions that should get a Stage One, 1200cc Sportster properly tuned for a balance of performance and smooth, reliable, street operation. The same principles will apply to 883 models and also to somewhat-upgraded (1250/1275) engine sizes, but altering ​the jets or needles ​to meet the needs of each particular engine.
  
-Stock Keihin needles & jets are often critical to a well operating carb. Note these comments by Joe Minton in reference to HD & aftermarket carb tuning kits: "The needle and needle jet in these kits are made of brass; the stock Keihin needle is polished hard-anodized aluminum, and the needle jet is hard brass. The brass-on-brass of the kit wears quickly and further richens an already too-rich mixture. The stock parts hardly wear at all. I have examined stock needles and jets with 45,000 to 70,000 miles of use and could not detect measurable wear."+Stock Keihin needles & jets are often critical to a well operating carb. Note these comments by Joe Minton in reference to HD & aftermarket carb tuning kits: "The needle and needle jet in these [aftermarket] ​kits are made of brass; the stock Keihin needle is polished hard-anodized aluminum, and the needle jet is hard brass. The brass-on-brass of the [aftermarket] ​kit wears quickly and further richens an already too-rich mixture. The stock parts hardly wear at all. I have examined stock needles and jets with 45,000 to 70,000 miles of use and could not detect measurable wear."
  
 +Trust the Keihin parts to provide good service and avoid problematic aftermarket kits.
  
 \\ \\
Line 69: Line 83:
  
 This process will give you a good rigid mount of the carb to the cylinder-heads while maintaining a good alignment of the carb with the manifold, all working together to eliminate those pesky intake air leaks.\\ This process will give you a good rigid mount of the carb to the cylinder-heads while maintaining a good alignment of the carb with the manifold, all working together to eliminate those pesky intake air leaks.\\
-((http://​xlforum.net/​forums/showthread.php?​postid=5342857#​post5342857))+((https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​181911-carb-questions?​postid=5342857#​post3887561))
 \\ \\
  
 **Check the Slide Diaphragm** - Be sure the slide operates correctly & the diaphragm is not torn or punctured. To do this, remove the air cleaner and reach your finger into the carb throat to the slide - push the slide up and quickly let the slide fall down. You should hear the vacuum sound as the slide returns to the bottom position. **Check the Slide Diaphragm** - Be sure the slide operates correctly & the diaphragm is not torn or punctured. To do this, remove the air cleaner and reach your finger into the carb throat to the slide - push the slide up and quickly let the slide fall down. You should hear the vacuum sound as the slide returns to the bottom position.
  
-This is from an [[http://​xlforum.net/​forums/showthread.php?​t=30748|XLForum thread]]: chrishajer wrote - CBAS5 and I were talking about what it should sound like, good, and we filmed that one. Then he said "you know, we should show a bad one too" so we did that. I think the [vacuum] sound and the speed that the slide comes down are the two most important things. Those things you can't describe to someone really. I can't anyway. But it's absolutely the best way to verify that the diaphragm is seated properly.+This is from an [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​18460-audio-and-video-of-cv-carb-diaphragm-good-and-bad?​t=30748|XLForum thread]]: chrishajer wrote - CBAS5 and I were talking about what it should sound like, good, and we filmed that one. Then he said "you know, we should show a bad one too" so we did that. I think the [vacuum] sound and the speed that the slide comes down are the two most important things. Those things you can't describe to someone really. I can't anyway. But it's absolutely the best way to verify that the diaphragm is seated properly.
  
  
Line 104: Line 118:
 More info & links here: [[:​techtalk:​evo:​carb02c|SubDoc - Why Not Dynojet Kits?]] More info & links here: [[:​techtalk:​evo:​carb02c|SubDoc - Why Not Dynojet Kits?]]
  
-**__To check for DynoJet parts, look at these 4 things:__** ((Identify DJ vs Keihin - http://​xlforum.net/​forums/showpost.php?​p=5238545))+**__To check for DynoJet parts, look at these 4 things:__** ((Identify DJ vs Keihin - https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​178513-01-1200c-jets-needle-issue#​post3816633))
   * Check the Needle: Stock is Nail-shaped - DJ has grooves & a clip   * Check the Needle: Stock is Nail-shaped - DJ has grooves & a clip
   * Check the Diaphragm/​Slide Spring: Stock is 6.0" - DJ is 5.75"   * Check the Diaphragm/​Slide Spring: Stock is 6.0" - DJ is 5.75"
Line 120: Line 134:
 ==== CV40 Needle, Jets & Idle Mixture Screw Parts ==== ==== CV40 Needle, Jets & Idle Mixture Screw Parts ====
  
-|  **Here are the genuine Keihin CV40 parts.\\ \\ Check your parts to be sure they match.** ​ | Be sure the Needle Jet is installed with\\ the long side up into the carb throat. | These are the parts for the\\ Idle Mixture Screw (IMS).\\ Install in correct order. | +|  **Here are the genuine Keihin CV40 parts.\\ Check your parts to be sure they match.** ​ | Be sure the Needle Jet is installed with\\ the long side up into the carb throat. | These are the parts for the\\ Idle Mixture Screw (IMS). | 
-| {{:​techtalk:​evo:​carb:​cv40-needle-em-jets.jpg?​360| Photo by IXL2Relax at the XLForum}} | {{:​techtalk:​evo:​carb:​cv40-needle-jet.jpg?​200| Annotated by IXL2Relax at the XLForum}} | {{:​techtalk:​evo:​carb:​cv-idlemixscrew.jpg?​150| }} |+| {{:​techtalk:​evo:​carb:​cv40-needle-em-jets.jpg?​360| Photo by IXL2Relax at the XLForum}} | {{:​techtalk:​evo:​carb:​cv40-needle-jet.jpg?​200| Annotated by IXL2Relax at the XLForum}} |  {{:​techtalk:​evo:​carb:​cv-idlemixscrew.jpg?​150|}} ​ \\ **Assemble in Correct Order**\\ Onto IMS Needle pointed up,\\ put the Spring, then Washer,\\ and O-Ring goes on top.  ​|
  
-From the factory, there is a cap over the Idle Mixture Screw. This needs to be removed to make IMS adjustments during tuning. It does not need to be replaced when done, but the cap is available as HD P/N 28015-01 if you would like to replace it when done making changes.((IMS Cap - http://​xlforum.net/​forums/showpost.php?p=595622&​postcount=9))+From the factory, there is a cap over the Idle Mixture Screw. This needs to be removed to make IMS adjustments during tuning. It does not need to be replaced when done, but the cap is available as HD P/N 28015-01 if you would like to replace it when done making changes.((IMS Cap - https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​27030-carb-jetting-i-can-t-see-this-issue-covered-elsewhere?​postcount=9#post612368))
  
 The Idle Mixture Screw "​packing"​ (spring, washer, o-ring) and the screw itself was never meant to be removed or tampered with, according to the MoCo, due to EPA regulations. This was adjusted and the screw covered with a soft aluminum cap at the factory before initial installation on your bike. None of these packing items are offered as replacement parts from your HD dealer, so you will need to look to the aftermarket suppliers for parts. The Idle Mixture Screw "​packing"​ (spring, washer, o-ring) and the screw itself was never meant to be removed or tampered with, according to the MoCo, due to EPA regulations. This was adjusted and the screw covered with a soft aluminum cap at the factory before initial installation on your bike. None of these packing items are offered as replacement parts from your HD dealer, so you will need to look to the aftermarket suppliers for parts.
Line 129: Line 143:
 To remove the IMS cap, carefully drill a small hole in the center of the cap (barely enough to make a hole). Be extremely careful not to overdrill into the cap because you will damage the screw that is behind the cap. Now, carefully twist in a sheetmetal screw about one thread, then pull on the screw to remove the cap. To remove the IMS cap, carefully drill a small hole in the center of the cap (barely enough to make a hole). Be extremely careful not to overdrill into the cap because you will damage the screw that is behind the cap. Now, carefully twist in a sheetmetal screw about one thread, then pull on the screw to remove the cap.
  
-An aftermarket kit (like E-Z-just) can be purchased with an extended screw head for hand tuning. It comes with the "​packing"​ in case yours has been damaged or is not functioning properly. But, check your local regulations before changing this out to an aftermarket part. You can also find, buy or barter for used parts. ("​Please note: it is a violation of federal law to tamper with or disable any emission or noise control device. That is your PSA for the day"​((XLForum member - chrishajer)) ((a/f screw packing photo by tchuck of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=183642)).+An aftermarket kit (like E-Z-just) can be purchased with an extended screw head for hand tuning. It comes with the "​packing"​ in case yours has been damaged or is not functioning properly. But, check your local regulations before changing this out to an aftermarket part. You can also find, buy or barter for used parts. ("​Please note: it is a violation of federal law to tamper with or disable any emission or noise control device. That is your PSA for the day"​((XLForum member - chrishajer)) ((a/f screw packing photo by tchuck of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​47776-idle-mixture-needle-mod?​t=183642)).
  
 **Checklist Of What You Have** - In order for others to provide quality advice, it is important that you know and can provide quality information about the build of your bike. Here's a list of important information for you to know and provide for TUNING of the CV carburetored EVOs (1986-2006):​ **Checklist Of What You Have** - In order for others to provide quality advice, it is important that you know and can provide quality information about the build of your bike. Here's a list of important information for you to know and provide for TUNING of the CV carburetored EVOs (1986-2006):​
  
 +^  Review These Considerations That Affect Tuning The CV40 Carburetor ​ ||
 +^  Device Question ​ ^  These Are Possible Answers - Be Specific About Your Config ​ |
 |Engine Size |(Stk883, Stk1200, Stk1100, Stk900, Stk1000, Conv883-1200,​ Conv883-1250,​ etc.)| |Engine Size |(Stk883, Stk1200, Stk1100, Stk900, Stk1000, Conv883-1200,​ Conv883-1250,​ etc.)|
 |Heads Installed |(Stock 883, Stock 1200, Specify Brand/​Model)| |Heads Installed |(Stock 883, Stock 1200, Specify Brand/​Model)|
 |Cam Installed |(Stock D, Stock W, Specify Brand/​Model)| |Cam Installed |(Stock D, Stock W, Specify Brand/​Model)|
-|Compression Test |( Min120PSI for 883 - Min150PSI for 1200 ) |+|Compression Test |( Min120PSI for 883 - Min150PSI ​for 1200 - 2004+ Min180PSI ​for 1200 ) |
 | | | | | |
 |Ignition Module |(Stock 883, Stock 1200, Specify Brand/​Model#​)| |Ignition Module |(Stock 883, Stock 1200, Specify Brand/​Model#​)|
Line 168: Line 184:
 |Fuel Float Valve |(Y/N - Cleaned & Checked, Replaced)| |Fuel Float Valve |(Y/N - Cleaned & Checked, Replaced)|
  
-| **TIP - 883 or 1200** ((Decman of the XLForum - xlforum.net/​forums/showpost.php?​p=3171730))\\ If you don't know your engine size, check it with a straw - Like this:\\ * Put in 5th gear\\ * Lift rear wheel\\ * Remove spark plugs\\ * Place a long plastic straw, chopstick, etc. in the spark plug hole\\ ​{{:​techtalk:​evo:​engmech:​measure-883-1200.jpg?​120|}}\\ * Rotate tire to move cylinder to bottom dead center - lowest straw position\\ * Check cylinder diagonal dimension from far bottom of cylinder to top lip of spark plug hole\\ * 883 bore 5.5" Diagonally ---- (Actual Bore Dia. is 3.000)\\ * 1200 bore 5.875" Diagonally - (Actual Bore Dia. is 3.498)\\ ​The plastic straw is unable to damage the cylinder and unlikely to fall into the cavity...\\ |+{{  :​techtalk:​evo:​engmech:​measure-883-1200.jpg?​170|}} ​**TIP - Do you have an 883 or 1200 size engine?** ((Decman of the XLForum - https://​www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​112707-telling-the-difference-between-a-1200-and-an-883#​post2368319)) {{:​common:​space100x5px.jpg?​direct&​140|}} ​\\ If you don't know your engine size, check it with a straw - Like this:\\ \\ * Put bike on lift or otherwise raise rear tire\\ * Put transmission ​in 5th gear\\ * Remove ​both spark plugs\\ * Place a long plastic straw, chopstick, etc. in the spark plug hole\\ \\ * Rotate tire to move cylinder to bottom dead center - lowest straw position\\ * Measure the cylinder diagonal dimension\\ * Check from far bottom of cylinder to top lip of spark plug hole\\ \\ * If 883 bore then 5.5" Diagonally ---- (Actual Bore Dia. is 3.000)\\ * If 1200 bore then 5.875" Diagonally - (Actual Bore Dia. is 3.498)\\ ​\\ Straw won'​t ​damage the cylinder and unlikely to fall into the cavity.\\ |
  
 \\ \\
Line 180: Line 196:
 ==== Check Items Ahead of the Carb ==== ==== Check Items Ahead of the Carb ====
  
 +  * On later models check for DTCs - These codes can indicate problem areas
   * Check your vacuum lines for good connection & no cracks   * Check your vacuum lines for good connection & no cracks
   * Check your VOES - that it switches with vacuum - later check switching point   * Check your VOES - that it switches with vacuum - later check switching point
 +    * or check your MAP sensor to be sure it is operating correctly
   * Check your gas tank for debris - remove & clean if needed   * Check your gas tank for debris - remove & clean if needed
   * Check your petcock for leaks (bad diaphragm) - Make sure vacuum petcocks open on vacuum   * Check your petcock for leaks (bad diaphragm) - Make sure vacuum petcocks open on vacuum
Line 200: Line 218:
   * Start with 175 or 180 Main Jet in Emulsion Tube (not critical until WOT settings)   * Start with 175 or 180 Main Jet in Emulsion Tube (not critical until WOT settings)
   * Start with 42 or 45 Idle Jet - Do not start with 46 or more - change later if needed   * Start with 42 or 45 Idle Jet - Do not start with 46 or more - change later if needed
 +    * Higher altitudes require less fuel for correct AFR - Jets may need reducing for altitude
   * Use a standard Keihin needle in slide (no washers to start) (1200 likes N65C Needle)   * Use a standard Keihin needle in slide (no washers to start) (1200 likes N65C Needle)
   * Use stock spring & needle cage (spider)   * Use stock spring & needle cage (spider)
Line 207: Line 226:
     * Be sure to reinstall pump rod correctly     * Be sure to reinstall pump rod correctly
   * Be sure you have removed each part, cleaned the ports & reinstalled correctly   * Be sure you have removed each part, cleaned the ports & reinstalled correctly
-  * Set the Idle Set Screw (located on the right side of the carb, near the throttle cables)\\ so that the Throttle Plate is between the Idle Port (one hole in the carb throat) and the\\ Transfer Ports (which consists of 5 holes nearby)+  * Set the Idle Set Screw (located on the right side of the carb, near the throttle cables)\\ so that the Throttle Plate is closed as much as possible. Try getting it between the Idle Port\\ (one hole in the carb throat) and the Transfer Ports (which consists of 5 holes nearby).\\ Don't obssess over it if you can't.
  
 \\ \\
Line 214: Line 233:
 ==== Setting The Float Level ===== ==== Setting The Float Level =====
  
-(Using a 1/2-inch spacer to lift the float side of the carb will approximate the 15°-20° angle needed.)\\ +(TIP: Using a 1/2-inch spacer to lift the float side of the carb will approximate the 15°-20° angle needed.)\\ 
-{{:​techtalk:​evo:​carb:​hd-cv40-floatlevel-instructions.jpg?​100|}}{{:​techtalk:​evo:​carb:​hd-cv40-floatlevel.jpg|}}\\ +**Click on the small image below for a larger version of the detailed instructions regarding setting the float level:**\\ 
-**Click on the small image above for the detailed instructions regarding setting the float level:** +{{:​techtalk:​evo:​carb:​hd-cv40-floatlevel-instructions.jpg?​direct&​250|}}{{:​techtalk:​evo:​carb:​hd-cv40-floatlevel.jpg|}}\\ 
 +\\
 {{:​techtalk:​evo:​carb:​cv40-floatvalve-02.jpg?​300|}}{{:​techtalk:​evo:​carb:​cv40-floatvalve-01.jpg?​400|}} {{:​techtalk:​evo:​carb:​cv40-floatvalve-02.jpg?​300|}}{{:​techtalk:​evo:​carb:​cv40-floatvalve-01.jpg?​400|}}
  
-In [[http://​xlforum.net/​forums/showthread.php?​t=2074492|This XLForum Thread]] there is a discussion of the float bowl overflowing and the possibility that it is caused by aftermarket float valves that are not of the proper design.((Images above by Hippysmack of the XLForum))+In [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​197805-carb-flooding?​t=2074492|This XLForum Thread]] there is a discussion of the float bowl overflowing and the possibility that it is caused by aftermarket float valves that are not of the proper design.((Images above by Hippysmack of the XLForum))
  
-** Tip for Inspecting ​Float Level - With Carb Installed **+** Tip for Checking Fuel/Float Level - With Carb Installed **
    
 HD advised of a tip for adjusting the float level thru Tech Tip #36 dated September 1993. \\ HD advised of a tip for adjusting the float level thru Tech Tip #36 dated September 1993. \\
Line 228: Line 247:
   * Checking carburetor float level can be easily done without even removing the carburetor from the motorcycle.   * Checking carburetor float level can be easily done without even removing the carburetor from the motorcycle.
   * Simply attach a section of clear model airplane fuel line to the float bowl overflow fitting.   * Simply attach a section of clear model airplane fuel line to the float bowl overflow fitting.
-  * Small diameter fuel line, which is compatible with gasoline, can be found in most hobby supply shops. +  * A small diameter fuel line, which is compatible with gasoline, can be found in most hobby supply shops. 
-  * Route the hose upward alongside the carburetor body. The motorcycle must be held level and be running to perform this test. +  * Route the hose upward alongside the carburetor body. 
-  * Open the float bowl drain screw and fuel will rise in the tube to the same level as that in the bowl itself. +  * The motorcycle must be held level and be running to perform this test. 
-  * A carburetor ​with a properly adjusted float level will have the fuel level in this hose at the joint between the carb body and the float bowl face.+  * Open the float bowl drain screw and fuel will rise in the hose to the same level as that in the bowl itself. 
 +  * In a carb with a properly adjusted float level the fuel level in this hose will be at the joint between the carb body and the float bowl face.
  
 \\ \\
Line 240: Line 260:
   * Check intake seals on manifold (at heads) - replace now while it's apart   * Check intake seals on manifold (at heads) - replace now while it's apart
   * Check intake seal between manifold & carb - replace now   * Check intake seal between manifold & carb - replace now
-  * Minimize Throttle Plate opening at idle - Set it between Idle Port & Transfer Ports [[http://​xlforum.net/​forums/showthread.php?​t=1635658|(See this XLForum thread)]]+  * Minimize Throttle Plate opening at idle - Set it between Idle Port & Transfer Ports if possible ​[[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​151434-cv-carb-transfer-ports?​t=1635658|(See this XLForum thread)]]
   * Check Idle Mixture Screw (IMS) screw/​spring/​washer/​o-ring condition - clean port   * Check Idle Mixture Screw (IMS) screw/​spring/​washer/​o-ring condition - clean port
   * Check IMS seat (Has the screw needle tip deformed the hole?)   * Check IMS seat (Has the screw needle tip deformed the hole?)
Line 255: Line 275:
 You'll need (4) screws that are 16mm in length for the float bowl. Then you'll need (3) screws that are 16mm in length and (1) screw that is 20mm in length for the Diaphragm Cover. If you choose to use **Button Socket Head** Screws for the top cover, they use a 2.5mm hex wrench. You'll need (4) screws that are 16mm in length for the float bowl. Then you'll need (3) screws that are 16mm in length and (1) screw that is 20mm in length for the Diaphragm Cover. If you choose to use **Button Socket Head** Screws for the top cover, they use a 2.5mm hex wrench.
  
-You can also replace the (3) Accelerator Pump screws with 4mm x 10mm long. ((rocketmangb & Folkie - http://​xlforum.net/​forums/showthread.php?t=635308))+You can also replace the (3) Accelerator Pump screws with 4mm x 10mm long. ((rocketmangb & Folkie - https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​84266-cv-carb-screw-kits?t=635308))
  
 Summary List:\\ Summary List:\\
 +[[techtalk:​ref:​tools804#​carburetor_intake_manifold_and_air_cleaner|Click Here]] for a full screw list on the fastener page in the Sportsterpedia.\\
 +
 4ea - 4mm x 16mm x .70TPI for Float Bowl\\ 4ea - 4mm x 16mm x .70TPI for Float Bowl\\
 3ea - 4mm x 16mm x .70TPI for Top Diaphragm Cover\\ 3ea - 4mm x 16mm x .70TPI for Top Diaphragm Cover\\
 1ea - 4mm x 20mm x .70TPI for Top Diaphragm Cover at Throttle Bracket\\ 1ea - 4mm x 20mm x .70TPI for Top Diaphragm Cover at Throttle Bracket\\
 3ea - 4mm x 10mm x .70TPI for Accelerator Pump\\ 3ea - 4mm x 10mm x .70TPI for Accelerator Pump\\
-Hex Head bolts use 3.0mm hex wrench\\+Hex Socket ​Head bolts use 3.0mm hex wrench\\
 Button Head bolts use 2.5mm hex wrench Button Head bolts use 2.5mm hex wrench
  
  
-( Also see: [[http://​xlforum.net/​vbportal/forums/showthread.php?​t=167074|XLF Thread 1]], [[http://​xlforum.net/​vbportal/forums/showthread.php?​t=1966443|XLF Thread 2]] & [[http://​xlforum.net/​vbportal/forums/showthread.php?​t=1792262|XLF Thread 3]], [[http://​xlforum.net/​vbportal/forums/showthread.php?​t=165259|XLF Thread 4]] )+( Also see: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​46148-stripped-my-float-bowl-screw-head-now-what?​t=167074|XLF Thread 1]], [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​182569-carb-float-bowl-screws?​t=1966443|XLF Thread 2]] & [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-general-discussion-and-problems/​166789-just-bought-a-used-sportster-checklists-for-making-it-right?​t=1792262|XLF Thread 3]], [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​46008-cv-needle-drawings-and-database?​t=165259|XLF Thread 4]] )
  
 As a reference, here are the OEM parts for the Carb Top Cover: As a reference, here are the OEM parts for the Carb Top Cover:
Line 283: Line 305:
 If you replace the screws on models that used a shoulder bolt, be careful not to overtighten the screws or you may crack the corner of the cover. [[https://​www.youtube.com/​watch?​v=zLHRLpaL1-E|Here'​s a video]] regarding installing brass ferrules when replacing the screws, should you choose to go that far. ((Video by bustert of the XLForum)) If you replace the screws on models that used a shoulder bolt, be careful not to overtighten the screws or you may crack the corner of the cover. [[https://​www.youtube.com/​watch?​v=zLHRLpaL1-E|Here'​s a video]] regarding installing brass ferrules when replacing the screws, should you choose to go that far. ((Video by bustert of the XLForum))
  
 +
 +\\
 +
 +==== Reinstall Slide, Diaphragm & Cover ====
 +To prevent tearing the Slide Diaphragm (reinstalling) - Shu: ((Shu from this XLF thread: https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​46148-stripped-my-float-bowl-screw-head-now-what?​t=167074+Post#​19))\\
 +  * Use four small dabs of wheel bearing grease in the seal channel spaced between the screw holes
 +  * Drop the slide into the carb (with needle, spider & spring in the center)
 +  * Reach inside the throat of the carb and raise the slide up a bit to lessen the tension at the seal
 +  * Seat the diaphragm seal in the channel of the carb
 +  * Install the carb top cover, centering the spring in the cover (while still holding the slide up)
 +  * Install the top screws (while holding the cover in place)
 +I've done it a ton of times on many carbs and never ripped a diaphram.\\
 +The problem comes when you try to do this without holding the slide up.
  
 \\ \\
Line 305: Line 340:
   * Be sure the Enrichener Knob is fully closed   * Be sure the Enrichener Knob is fully closed
   * Set the IMS  - See the “Idle Drop Method” mentioned below   * Set the IMS  - See the “Idle Drop Method” mentioned below
-  * Adjust ​Idle Set Screw so bike idles well 950-1050 RPMs+  * After tuning, adjust ​Idle Set Screw so bike idles well at 950-1050 RPMs
  
 **Check Accelerator Pump** **Check Accelerator Pump**
-  * Check Accelerator pump - Twist throttle, see that it squirts directly at main needle+  * Check Accelerator pump - Twist throttle, see that it squirts directly at the needle
   * See the expanded explanation of the Accelerator Pump operation listed below   * See the expanded explanation of the Accelerator Pump operation listed below
  
 **Check Transfer Operation** **Check Transfer Operation**
   * Check Response to Blipping the Throttle (while parked) - should be crisp & responsive   * Check Response to Blipping the Throttle (while parked) - should be crisp & responsive
- 
  
 \\ \\
  
-==== The Idle/​Transfer ​Ports Operation & Tuning ====+==== General Comments about Idle/​Transfer Tuning ====
  
-Every carb is a little ​different, so the tuning must be done while monitoring the engine response. All the parts must work correctly so it's best to check & set some parts beforehand. This can prevent distortion of the carb operation and your results.+Every bike/​engine/​carb/exhaust combination functions ​a little ​differently, so tuning ​the carb must be done while monitoring the engine response. All the parts must work correctly so it's best to check & set some parts before starting the tuning. This can prevent distortion of the carb operation and your results.
  
-Because of the constant-velocity design, where the vacuum slide works as a partner with the throttle plate, the throttle being wacked open DOES NOT equate to the carb operating at wide open. The vacuum slide responds to the throttle plate opening, and increases the size of the carb venturi, in response to the change in vacuum. More vacuum in the slide chamber, ahead of the open throttle plate causes the slide to create a larger venturi. In essence, the vacuum slide makes the CV carb operate as a variable-venturi carb, becuase ​the size of the throat opening is altered by the vacuum slide.+Because of the constant-velocity design, where the vacuum slide works as a partner with the throttle plate, the throttle being wacked open DOES NOT equate to the carb operating at wide open. The vacuum slide responds to the throttle plate opening, and increases the size of the carb venturi, in response to the change in vacuum. More vacuum in the slide chamber, ahead of the open throttle plate causes the slide to create a larger venturi. In essence, the vacuum slide makes the CV carb operate as a variable-venturi carb, because ​the size of the throat opening is altered by the vacuum slide rising & falling.
  
-Reference the pictures above & below to identify the various parts during the explanation of their operation.+  * Reference the pictures above & below to identify the various parts during the explanation of their operation.
  
-The Idle Port is intended to supply the necessary fuel mix when the engine is idling, but it also continues to help feed fuel mix during the transfer operation and minimal speed cruising. The Transfer Ports are intended to add more fuel mix when the throttle plate begins to open during the period between idling and the mid-range operation of the engine. If the throttle is opened quickly, the Accelerator Pump will supply a shot of fuel to mix with the increased air passing thru the venturi.+The Idle Port is intended to supply the necessary fuel mix (AFR) when the engine is idling, but it also continues to help feed fuel mix during the transfer operation and minimal speed cruising. The Transfer Ports are intended to add more fuel mix when the throttle plate begins to open during the period between idling and the mid-range operation of the engine. If the throttle is opened quickly, the Accelerator Pump will supply a shot of fuel to mix with the increased air passing thru the venturi.
  
-The Transfer Ports continue to actively supply fuel for the carb operation, although, as the throttle/​slide/​needle increase the engine speed, the Transfer Ports represent a smaller & smaller percentage of the overall fuel supplied & consumed. However, when cruising at a minimum speed (with the throttle plate barely open), the Transfer Ports are an important part of (along with the needle in the needle jet) supplying fuel for the carb operation.+The Transfer Ports continue to actively supply fuel for the carb operation, although, as the throttle/​slide/​needle increase the engine speed, the Transfer Ports represent a smaller & smaller percentage of the overall fuel supplied & consumed. However, when cruising at a minimum speed (with the throttle plate barely open), the Transfer Ports are an important part of supplying fuel for the carb operation, ​along with the needle in the needle jet.
  
 The mid-range operation is mostly handled by the needle position in the needle jet, followed by the main jet metering fuel when the throttle/​slide/​engine is operating at Wide Open Throttle, with the needle fully retracted from the needle jet. The mid-range operation is mostly handled by the needle position in the needle jet, followed by the main jet metering fuel when the throttle/​slide/​engine is operating at Wide Open Throttle, with the needle fully retracted from the needle jet.
  
-**Discussion Thread** regarding ​the relationship between ​the Transfer Ports and the Slow Jet (AKA Pilot Jet): [[http://​xlforum.net/​forums/​showthread.php?​t=1635658 ]] ((Article from XLForum member IXL2Relax))+The selected needle effects ​the overall operation of the carb. Plus, initially, you don't want the Main Jet to cause any lean conditions while you're riding the bike to verify idle & transfer operations, so the Main Jet should be at least a 175 or 180.
  
 +The needle is also important relative to testing the transition between idle & mid-range throttle operation because you are transitioning to using the needle. There were many different needles and main jet combinations supplied on various models. Making modifications to air cleaners & exhausts also present a myriad of different conditions. Sometimes, using the stock needle is fine for getting the right AFR across the operating range. This is often true with the 883 models. Other times, you may need to replace the stock needle with an N65C needle (which creates a better overall AFR than the stock needle) since it has been found to work well on 1200cc models. Experimenting with other needles or raising the base level of the needle with washers is a common way of altering the AFR for the mid and upper range operation of the carb.
  
-It is important to have the correctly sized Main Jet & Needle for the overall operation of the carb. You do not want an excessively lean AFR in any part of the carb operation. They are also important to properly testing the transition between ​idle & mid-range throttle operation. You can get a good starting point for a Stage One 1200 engine using a 175 main jet along with an N65C needle (which are a little richer than most stock parts). Later, you will need to verify whether ​those particular ​selections ​fit exactly what you need. You can use tuning methods for mid-range and wide-open-throttle operation to evaluate your choices. ​But, those parts are not directly involved in tuning ​the idle & transfer functions.+After getting ​the idle & transfer operations set correctly, you will need to verify whether ​the needle & main jet selections ​work properly over the entire carb operation range. You can use tuning methods for mid-range and wide-open-throttle operation to evaluate your choices. 
 + 
 +==== Descriptions of the Operating Parts ====
  
 **Main Jet** - The Main Jet itself does not begin to limit fuel delivery to the carb operation until the vacuum slide is 75-90% wide open and the engine is revving. Until then, other parts & factors (such as the idle mixture screw, slow-jet and needle position in the needle jet) are controlling the fuel utilized by the carb. **Main Jet** - The Main Jet itself does not begin to limit fuel delivery to the carb operation until the vacuum slide is 75-90% wide open and the engine is revving. Until then, other parts & factors (such as the idle mixture screw, slow-jet and needle position in the needle jet) are controlling the fuel utilized by the carb.
Line 340: Line 377:
 **Needle & Needle Jet** - The needle is a tapered, nail-like, rod that operates from the bottom of the slide into the needle jet. It does not affect the flow of fuel until the throttle plate opens sufficiently to create an active vacuum in the outer section of the venturi, which will lift the slide and move the needle in the needle jet. The fuel mix supplied thru the needle jet, by your selected needle and the emulsion tube, will combine with the transfer fuel mix of the slow jet as the carb operation moves out of the transfer period into the mid-range of the throttle/​slide function. **Needle & Needle Jet** - The needle is a tapered, nail-like, rod that operates from the bottom of the slide into the needle jet. It does not affect the flow of fuel until the throttle plate opens sufficiently to create an active vacuum in the outer section of the venturi, which will lift the slide and move the needle in the needle jet. The fuel mix supplied thru the needle jet, by your selected needle and the emulsion tube, will combine with the transfer fuel mix of the slow jet as the carb operation moves out of the transfer period into the mid-range of the throttle/​slide function.
  
-The main jet, located at the bottom of the emulsion tube, is way below where the needle rides and has no relationship with what the needle does other than to create an eventual upper fuel limit at WOT. ((wedge of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?​t=1820463&​page=9)) The needle rides in the needle jet which is the silver jet (hollow cylinder) that sticks up from the bottom of the throat of the carb and the needle moves up and down thru it during operation.+The main jet, located at the bottom of the emulsion tube, is way below where the needle rides. It has no variable ​relationship with what the needle does except ​to create an eventual upper fuel limit at WOT, when the needle is fully out of the needle jet. ((wedge of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​169629-read-my-plugs/​page9?​t=1820463&​page=9)) The needle rides in the needle jet which is the silver ​colored ​jet (hollow cylinder) that sticks up from the bottom of the throat of the carb. The tapered ​needle moves up and down thru this constant orifice ​during ​the vacuum slide operation.
  
-The tapered ​needle and needle jet together ​control fuel flow coming out of the emulsion tube into the throat. After the needle is almost up and out of the needle jet, then the main jet will become the limiting factor for the fuel flow at the wide open throttle position (WOT). Until the needle gets out of the way, the main jet is doing nothing to limit the needed fuel.+The space between the needle and needle jet control fuel flow coming out of the emulsion tube into the throat. After the needle is out of the needle jet, then the main jet will become the limiting factor for the fuel flow at the wide open throttle position (WOT). Until the needle gets out of the way, the main jet is doing nothing to limit the needed fuel.
  
-( See this [[http://​xlforum.net/​forums/showthread.php?​t=165259|XLForum Thread]] ​on needle ​dimensions)+Significant Comment by Don Burton from this detailed discussion of __some of the needle dimensions__ at [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​46008-cv-needle-drawings-and-database?t=165259|this interesting ​XLForum Thread]]:\\ 
 +"Also, elsewhere someone has measured the inside diameter of the needle jet (the needle jet, not the jet needle) ​as being just .114 of an inch. If so, that explains why just .001 of an inch difference in diameter of the straight portion of the needle (usually measures between .107-.110, depending upon the needle) makes a significant difference in air/fuel ratio at just above off idle and in the lower throttle settings."​
  
-**Emulsion Tube** ((stevo of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?t=2876))- As the throttle plate is opened further the main circuit comes into play. Fuel enters the bottom of the emulsion tube thru the main jet. Air enters thru the main air bleed jet in the front of the carb. The air and fuel are mixed in the emulsion tube before this fuel mixture passes up the tube past the needle jet and needle into the carb venturi and down the intake chasing after (combining with) the idle circuit fuel mix. The size, number and position of the holes in the emulsion tube effect the fuel delivery. More holes = more air = leaner mixture. More holes at the top = leaner mixture at low speeds. More holes at the bottom = leaner mixture at high speeds. If you change emulsion tubes you need to use a compatible needle. It will also have an effect on the main jet size (at WOT) and quite often the pilot circuit thru the just-off-idle response. Needles, needle jet, emulsion tube (size, position and amount of holes), main air bleed size and main jet are all closely linked. Changing one can affect the others and all have an affect on the fuel delivery to differing amount at different throttle positions.+**Emulsion Tube**((stevo of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​1974-question-about-function-of-the-emulsion-tube?t=2876))- As the throttle plate is opened further the main circuit comes into play. Fuel enters the bottom of the emulsion tube thru the main jet. Air enters thru the main air bleed jet in the front of the carb. The air and fuel are mixed in the emulsion tube before this fuel mixture passes up the tube past the needle jet and needle into the carb venturi and down the intake chasing after (combining with) the idle circuit fuel mix. The size, number and position of the holes in the emulsion tube effect the fuel delivery. More holes = more air = leaner mixture. More holes at the top = leaner mixture at low speeds. More holes at the bottom = leaner mixture at high speeds. If you change emulsion tubes you need to use a compatible needle. It will also have an effect on the main jet size (at WOT) and quite often the pilot circuit thru the just-off-idle response. Needles, needle jet, emulsion tube (size, position and amount of holes), main air bleed size and main jet are all closely linked. Changing one can affect the others and all have an affect on the fuel delivery to differing amount at different throttle positions.
  
  
-**Throttle Plate** - To assure the throttle plate is capable of closing completely, back out the idle set screw (on the side of the carb near the throttle cable cam) so that it is not limiting the closing of the throttle plate.* Make sure the throttle plate rotates smoothly with the throttle cable cam. Set the position of the throttle plate, with the idle set screw, so that the bottom edge of the plate is closed just past the transfer port holes and is thus located between the single idle port hole and the multiple holes of the transfer ports. In practice, this is easier on some CV40 carbs than others. Do what you can to keep the plate as closed as possible, but don't obssess ​on getting it exactly between those port holes. Your viewing angle is skewed when looking in there, anyway.+**Throttle Plate** - To assure the throttle plate is capable of closing completely, back out the idle set screw (on the side of the carb near the throttle cable cam) so that it is not limiting the closing of the throttle plate.* Make sure the throttle plate rotates smoothly with the throttle cable cam. Set the position of the throttle plate, with the idle set screw, so that the bottom edge of the plate is closed ​as much as possible for setting the idle operation. Try getting it just past the transfer port holes and thus located between the single idle port hole and the multiple holes of the transfer ports. In practice, this is easier on some CV40 carbs than others. Do what you can to keep the plate as closed as possible, but DON'T OBSSESS ​on getting it exactly between those port holes. Your viewing angle is skewed when opening the throttle plate and looking in the venturi, anyway, so you see the hole before the plate is completely beyond it.
  
-(* If the throttle plate appears not to close fully with the idle screw fully wound out, carefully ​loosen the two throttle plate mounting screws, slightly. After the throttle plate is fully closed and has centered itself in the venturi, retighten the two mounting screws (don't overtighten & strip the threads). If by chance, for any reason, you have the throttle plate completely off, be aware that there is a right & wrong way to reinstall it. Be sure the plate is remounted with the right orientation because the top & bottom have an angled edge that needs to properly meet the carb venturi.)+(* It doesn'​t happen often, but if the throttle plate appears not to close fully with the idle screw fully wound out, it may need to be recentered in the throat. Carefully ​loosen the two throttle plate mounting screws, slightly. After the throttle plate is fully closed and has centered itself in the venturi, ​start to retighten the two mounting screws (don't overtighten & strip the threads) ​while opening & closing the throttle so the plate squares up with the shaft but also recenters in the venturi. If by chance, for any reason, you have the throttle plate completely off, be aware that there is a right & wrong way to reinstall it. Be sure the plate is remounted with the right orientation because the top & bottom have an angled edge that needs to properly meet the carb venturi.)
  
 {{ :​techtalk:​evo:​carb:​cv40-imscap-drillbit.jpg?​200|}} {{ :​techtalk:​evo:​carb:​cv40-imscap-drillbit.jpg?​200|}}
-**IMS Cap** - From the factory, the cavity for the Idle Mixture Screw (IMS) is covered with a small cap. (Note from the service manual: Adjusting mixture setting by procedures other than those specified in the manual may be in violation of local regulations.) The following procedures are not specified in the manual. To remove the cap and gain access to the IMS, use a small drill bit to create a hole in the cap. Use several layers of tape on the drill bit to limit the depth the bit can penetrate the cap. If you pop thru the cap too deep with the bit, you may damage the internal screw head - Be Careful. Once your cap has a hole in it, CAREFULLY thread a self-tapping screw (blunt nose) into the hole JUST ENOUGH to capture the cap & pull it out of the IMS cavity. ((photo by cantolina of the XLFORUM ​http://​xlforum.net/​forums/showthread.php?t=14949))+**IMS Cap** - From the factory, the cavity for the Idle Mixture Screw (IMS) is covered with a small cap. (Note from the service manual: Adjusting mixture setting by procedures other than those specified in the manual may be in violation of local regulations.) The following procedures are not specified in the manual. To remove the cap and gain access to the IMS, use a small drill bit to create a hole in the cap. Use several layers of tape on the drill bit to limit the depth the bit can penetrate the cap. If you pop thru the cap too deep with the bit, you may damage the internal screw head - Be Careful. Once your cap has a hole in it, CAREFULLY thread a self-tapping screw (blunt nose) into the hole JUST ENOUGH to capture the cap & pull it out of the IMS cavity.((photo by cantolina of the XLFORUM ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​9621-carb-adjusting-where-are-the-jets-and-the-mixture-screw?​t=14949)) ​If you want to replace the cap, it is HD P/N 28015-01. 
 + 
 +**Slow Jet, Transfer Ports, Idle Port & Idle Mixture Screw** - As illustrated below, these parts function in a close relationship. The size of the Slow Jet creates a fuel mixture that is delivered to the Transfer Ports (5 openings), but is also flowed to the Idle Mixture Screw (IMS). The IMS is adjusted in small increments to allow some of the fuel mixture (from the Slow Jet) to be flowed thru the Idle Port (one opening). In this way, while both the Idle Port & the Transfer Ports are dependent on the Slow Jet, the amount of fuel to the Idle Port fuel can be controlled separately from the Transfer Ports by using the Idle Mixture Screw. A more detailed description of this operaiton follows this brief overview. 
 + 
 +**Note:** There is an XLForum discussion thread regarding the relationship between the Transfer Ports and the Slow Jet (AKA Pilot Jet): [[https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​151434-cv-carb-transfer-ports?​t=1635658]] ((Article from XLForum member IXL2Relax)) 
  
 {{:​techtalk:​evo:​carb:​cv40-idletransferports.jpg|}} ​    ​{{:​techtalk:​evo:​carb:​cv40-idletransfer-diagram.jpg|}} {{:​techtalk:​evo:​carb:​cv40-idletransferports.jpg|}} ​    ​{{:​techtalk:​evo:​carb:​cv40-idletransfer-diagram.jpg|}}
  
-**INTERACTIONS OF JETS PORTS - A balancing act**+ 
 +==== Interaction of Jets Ports - A Balancing Act ====
  
 The Slow Jet (AKA: Pilot Jet or Idle Jet) along with the Idle Mixture Screw (IMS) determines the quantity & quality of the Idle Fuel Mix, while the Slow Jet alone determines the Transfer Fuel Mix. It is an important balancing chore to get all the parts involved in the Idle & Transfer functions to work well together to meet the needs of the engine operating range. As you change one part or setting, it may require making changes in other settings in order to keep or find the proper balance of the different fuel circuits. This balancing concept also applies to the mid-range and wide-open-throttle operations. The Slow Jet (AKA: Pilot Jet or Idle Jet) along with the Idle Mixture Screw (IMS) determines the quantity & quality of the Idle Fuel Mix, while the Slow Jet alone determines the Transfer Fuel Mix. It is an important balancing chore to get all the parts involved in the Idle & Transfer functions to work well together to meet the needs of the engine operating range. As you change one part or setting, it may require making changes in other settings in order to keep or find the proper balance of the different fuel circuits. This balancing concept also applies to the mid-range and wide-open-throttle operations.
Line 376: Line 420:
 Having gained access to the IMS, it is recommended that you start by opening the IMS from GENTLY seated to 2-1/2 turns CCW. This setting is likely to be larger than the factory setting, which is often in the 1 to 1-1/2 turns range. By opening the IMS more, we are richening the Idle Fuel Mix to provide addition fuel during idle & transfer operations.This may also help the engine run cooler. Having gained access to the IMS, it is recommended that you start by opening the IMS from GENTLY seated to 2-1/2 turns CCW. This setting is likely to be larger than the factory setting, which is often in the 1 to 1-1/2 turns range. By opening the IMS more, we are richening the Idle Fuel Mix to provide addition fuel during idle & transfer operations.This may also help the engine run cooler.
  
-**Thus far,** the throttle plate has been positioned between the Idle Port & the Transfer Ports, the Slow Jet has been chosen as stock or a 45 if the engine is 1200 or Stage One, the IMS cap was removed and the IMS was adjusted to 2-1/2 turns out from GENTLY seated. In addition, a selected needle was installed in the slide along with a reasonable choice for the Main Jet. These parts and settings were selected to provide a valid STARTING POINT for further, more accurate, adjustments.+**Thus far,** the throttle plate has been positioned ​(as much as possible) ​between the Idle Port & the Transfer Ports, the Slow Jet has been chosen as stock or a 45 if the engine is 1200 or Stage One, the IMS cap was removed and the IMS was adjusted to 2-1/2 turns out from GENTLY seated. In addition, a selected needle was installed in the slide along with a reasonable choice for the Main Jet. These parts and settings were selected to provide a valid STARTING POINT for further, more accurate, adjustments.
  
 While the proper idle rpm will be set AFTER adjusting the IMS setting (using the Idle Speed Screw), it is important to isolate the Idle Port operation from the Transfer Ports. While the proper idle rpm will be set AFTER adjusting the IMS setting (using the Idle Speed Screw), it is important to isolate the Idle Port operation from the Transfer Ports.
Line 383: Line 427:
  
  
-At this point, we need the engine to be warmed up to normal operating temperature to continue tuning the carb. A cold engine may operate quite differently once warmed up, therefore, tuning the carb while the engine is cold is not valid.+At this point, we need the engine to be warmed up to normal operating temperature to continue tuning the carb. A cold engine may operate quite differently once warmed up, therefore, tuning the carb while the engine is cold is not usually successful.
  
-Start the engine and use the enrichener ​if the engine is coldfor the first minute or so, while you take the bike for a 10-15 minute ride to warm the engine fully. Then be careful of the burn potential while working around a hot engine. Make sure you have no intake leaks in the manifold seals by using an unlit propane torch to flow propane around ​those seals. The engine idle will alter if an intake leak allows propane into the manifold.+Start the engine and use the enrichener ​(since ​the engine is coldfor the first 30-90 seconds, while you take the bike for a 10-15 minute ride to warm the engine fully. Then be careful of the burn potential while working around a hot engine ​and even hotter exhaust. Make sure you have no intake leaks in the manifold seals by using an unlit propane torch to flow propane around ​all three manifold ​seals. The engine idle will alter if an intake leak allows propane into the manifold.
  
-==== The Idle Drop Method (IDM) ==== 
  
-The Idle Drop Method (IDM) will help find the right setting ​for the Idle Mixture Screw (IMS)((see the chrishajer thread link below)). At idle, the engine will have difficulty if the idle fuel mix is too lean or if the idle fuel mix is too rich. There is a small range between those excesses, which is the point of this adjustment. This procedure does require the correct Slow Jet, so you may need to change the Slow Jet if you cannot find the described idle range while performing the IDM.+==== The Idle Drop Method (IDM) for Setting ​Idle Fuel ====
  
-If you have previously set the throttle plate, between the idle port and the transfer ports, using the Idle Set Screw, you may need to roll the throttle slightly to keep the engine idle. With the throttle grip, set the idle speed as low as possible, yet still smooth engine operation. Lock the idle speed with the throttle grip lock (rather than changing the setting of the Idle Set Screw, which should still be between the Idle Port & the Transfer Ports).+The Idle Drop Method (IDM) will help find the right setting for the Idle Mixture Screw (IMS) to supply the proper fuel mix to the Idle Port.((see the chrishajer thread link below)). At idle, the engine will have difficulty if the idle fuel mix is too lean or if the idle fuel mix is too rich. There is a small range between those excesses, which is the point of this adjustment. This procedure does require the correct Slow Jet, so you may need to change the Slow Jet if you cannot find the described idle range while performing the IDM. 
 + 
 +If you have previously set the throttle plate, between the idle port and the transfer ports, using the Idle Set Screw, you may need to roll the throttle slightly ​(at the beginning of this process) ​to keep the engine idle. With the throttle grip, set the idle speed as low as possible, yet still smooth engine operation. Lock the idle speed with the throttle grip lock (rather than changing the setting of the Idle Set Screw, which should still be (as close as possible) ​between the Idle Port & the Transfer Ports).
  
 Now carefully reach under the carb and adjust the IMS with very small increments, turning it counter-clockwise (as if looking up from below). This is enrichening the fuel mix. Listen for the engine speed to begin faltering, then STOP adjusting the screw. Now begin turning the IMS clockwise with very small movements. Listen for the engine speed to return to running well and then begin faltering as you continue to turn the screw clockwise, which will create a lean condition. When it falters, STOP adjusting the screw. Now carefully reach under the carb and adjust the IMS with very small increments, turning it counter-clockwise (as if looking up from below). This is enrichening the fuel mix. Listen for the engine speed to begin faltering, then STOP adjusting the screw. Now begin turning the IMS clockwise with very small movements. Listen for the engine speed to return to running well and then begin faltering as you continue to turn the screw clockwise, which will create a lean condition. When it falters, STOP adjusting the screw.
Line 398: Line 443:
  
  
-| **Note - Trouble Finding A Change** - You may still have the throttle plate too far open, thereby running on the Transfer Ports instead of the Idle Port. But, if you have carefully set the throttle plate & still can't find a fall off until below 1/2 turn out, you need a smaller Slow Jet. If you can't find a fall off in idle until beyond 3-1/2 turns out, you need a larger Slow Jet. However, it is not recommended to use a smaller size than 42 nor larger size than 46. If the IMS setting appears to make no difference, you may have other issues. You may have an intake leak or exhaust leak. You may have fuel leaking into the carb thru the vacuum hose because of a defective petcock diaphragm or thru a defective Accelerator Pump diaphragm.((oldboy at Post#7 - http://​xlforum.net/​forums/showthread.php?​t=2076811)) Be sure to double check the throttle plate position. ​ |+| **Note - Trouble Finding A Change** - You may still have the throttle plate too far open, thereby running on the Transfer Ports instead of the Idle Port. But, if you have carefully set the throttle plate & still can't find a fall off until below 1/2 turn out, you need a smaller Slow Jet. If you can't find a fall off in idle until beyond 3-1/2 turns out, you need a larger Slow Jet. However, it is not recommended to use a smaller size than 42 nor larger size than 46. If the IMS setting appears to make no difference, you may have other issues. You may have an intake leak or exhaust leak. You may have fuel leaking into the carb thru the vacuum hose because of a defective petcock diaphragm or thru a defective Accelerator Pump diaphragm.((oldboy at Post#7 - https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​199875-turning-idle-mixture-screw-no-effect?​t=2076811)) Be sure to double check the throttle plate position. ​ |
  
  
-**Once you have found the range,** use the counting you made (of the number of 1/8 turns) in order to make a setting of the IMS in the near center of the range you moved the screw from TOO RICH to TOO LEAN. For instance, if after finding the TOO RICH (CCW) setting, you then counted turning the screw SIX 1/8 turns (going CW) when you found the TOO LEAN condition, you would NOW turn the screw back (CCW) THREE 1/8 turns in order for it to be in the center of the range that operated well.+**Once you have found the range,** use the counting you made (of the number of 1/8 turns) in order to make a setting of the IMS in the near center of the range you moved the screw from TOO RICH to TOO LEAN. For instance, if after finding the TOO RICH (CCW) setting, you then counted turning the screw SIX 1/8 turns (going CW) when you found the TOO LEAN condition, you would NOW turn the screw back (CCW) THREE 1/8 turns in order for it to be in the center of the range that operated well. In fact, to be on the safe side of that setting, you  might want to go an extra 1/16 to 1/8 turn more rich.
  
 You can try this several times to assure yourself that you found the TOO RICH condition (CCW), then found the TOO LEAN condition (CW) and then were able to set the IMS (CCW) at the center between those. If the idle increases significantly during the adjustment, turn the throttle down to lower the RPMs and do the check again. You can try this several times to assure yourself that you found the TOO RICH condition (CCW), then found the TOO LEAN condition (CW) and then were able to set the IMS (CCW) at the center between those. If the idle increases significantly during the adjustment, turn the throttle down to lower the RPMs and do the check again.
  
-The goal is to have the engine properly idle from the Slow Jet the Idle Mixture Screw rather than by opening ​the throttle plate with the Idle Set Screw or throttle grip. Once you are satisfied that you did find the proper setting, you can turn the bike off.+The goal is to have the engine properly idle without using any fuel from the Transfer Ports. It should idle using only the Slow Jetthe Idle Mixture Screw & the Idle Port. It should not require you to open the throttle plate with the Idle Set Screw or throttle grip. Once you are satisfied that you did find the proper setting, you can turn the bike off.
  
-Now check to see how many turns you must go (clockwise) until you GENTLY seat (closed) the IMS. **__WRITE DOWN THIS SETTING.__** ​Now put the IMS back to where it belongs. That's it - You completed the Idle Mixture Screw setting using the Idle Drop Method.+Now check to see how many turns you must go (clockwise) until you GENTLY seat (closed) the IMS. **__WRITE DOWN THIS SETTING.__** ​This is the number of turns out from a gentle seat to the correct IMS setting. Put the IMS back (using your count) ​to where it belongs. That's it - You completed the Idle Mixture Screw setting using the Idle Drop Method.
  
 You can now release the throttle lock. Start the engine & adjust the Idle Set Screw (it should require very little adjustment) for the proper idle speed, typically, it should be set between 950 & 1050 RPMs. You can now release the throttle lock. Start the engine & adjust the Idle Set Screw (it should require very little adjustment) for the proper idle speed, typically, it should be set between 950 & 1050 RPMs.
Line 422: Line 467:
 Doing a stage one upgrade with free flowing air cleaner and exhausts will create an even leaner condition than that from the factory configuration. In that case, start from general tuning and fix the overall lean condition. Doing a stage one upgrade with free flowing air cleaner and exhausts will create an even leaner condition than that from the factory configuration. In that case, start from general tuning and fix the overall lean condition.
  
-These comments on the XLForum are from Stevo ((Post#31 - XLForum thread: ​http://​xlforum.net/​forums/showthread.php?t=30561))+These comments on the XLForum are from Stevo ((Post#31 - XLForum thread: ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​18344-cv-carb-mod-to-reduce-carb-farts?t=30561))
 | A carb fart is basicly caused by a lean condition... often from not having enough fuel when cold or from lack of vacuum from blipping or opening the throttle too quickly... (A mikuni will do it if you open it too quickly.) Too much air is entering the intake plenum for the amount of fuel for those particualr engine requirements at that point in time.. ie : it's too lean..\\ \\ The leaner [the condition]... the crisper [the fart]... until ya get too lean and then it pops thru the intake.\\ [On the other hand} A fart thru the exhaust or flat sound is usually from a rich condition.| | A carb fart is basicly caused by a lean condition... often from not having enough fuel when cold or from lack of vacuum from blipping or opening the throttle too quickly... (A mikuni will do it if you open it too quickly.) Too much air is entering the intake plenum for the amount of fuel for those particualr engine requirements at that point in time.. ie : it's too lean..\\ \\ The leaner [the condition]... the crisper [the fart]... until ya get too lean and then it pops thru the intake.\\ [On the other hand} A fart thru the exhaust or flat sound is usually from a rich condition.|
  
-And these from Chris Hajer ((Post#8 - XLForum thread: ​http://​xlforum.net/​forums/showthread.php?t=30561))+And these from Chris Hajer ((Post#8 - XLForum thread: ​https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​18344-cv-carb-mod-to-reduce-carb-farts?t=30561))
 | When blipping the throttle, two things happen:\\ \\ 1. You are shooting some fuel in with the accelerator pump.\\ 2. When you blip the throttle, you are actually opening the throttle plate, and that larger opening causes a very [quick/​temporary] minor drop in velocity through the carb and reduces the signal (vacuum, pull) across the fuel jets, so you flow less fuel for an instant. The accelerator pump is supposed to compensate for that somewhat. The problem is, with a very short stroke of the accelerator pump rod, like a blip does, not much if any fuel is actually shot, so the pump is not doing its job, in some cases. | | When blipping the throttle, two things happen:\\ \\ 1. You are shooting some fuel in with the accelerator pump.\\ 2. When you blip the throttle, you are actually opening the throttle plate, and that larger opening causes a very [quick/​temporary] minor drop in velocity through the carb and reduces the signal (vacuum, pull) across the fuel jets, so you flow less fuel for an instant. The accelerator pump is supposed to compensate for that somewhat. The problem is, with a very short stroke of the accelerator pump rod, like a blip does, not much if any fuel is actually shot, so the pump is not doing its job, in some cases. |
  
-The second thing to say is that **YOU MUST** get a great tune from everything else before addressing the farts, because fixing other issues may eliminate or minimize the farts anyway. So, get your **timing** set correctly, get your **fuel flow** maximized and make certain you have no **air intake leaks.** Get your **throttle plate** set right (between idle & transfer ports), choose the right idle jet and use the Idle Drop Method to get the **Idle Mixture Screw** (IMS) set correctly. Make sure the bike is thoroughly warmed up before tuning. Each of these areas will need specific settings to match your engine build, whether stock, stage one, 1200/​1250/​1275 conversion, cams, etc. __BE SURE YOU READ ALL OF THE CARB TUNING INFORMATION IN THIS SECTION.__+The second thing to say is that **YOU MUST** get a great tune from everything else before addressing the farts, because fixing other issues may eliminate or minimize the farts anyway. So, get your **timing** set correctly, get your **fuel flow** maximized and make certain you have no **air intake leaks.** Get your **throttle plate** set right (as much as possible ​between idle & transfer ports), choose the right idle jet and use the Idle Drop Method to get the **Idle Mixture Screw** (IMS) set correctly. Make sure the bike is thoroughly warmed up before tuning. Each of these areas will need specific settings to match your engine build, whether stock, stage one, 1200/​1250/​1275 conversion, cams, etc. __BE SURE YOU READ ALL OF THE CARB TUNING INFORMATION IN THIS SECTION.__
  
 The third thing to say is that it should be obvious that to correct a lean condition we need to add fuel to the mix (unless an air leak is the cause of the lean condition). But we need to add fuel carefully to address this quick, temporary, lean condition without drowning the entire carb operating range in extra fuel. A typical response is to increase the idle jet, but if you increase the idle jet larger than a size 45 or 46 you are flooding too much fuel into the transfer ports and the overall mix. The third thing to say is that it should be obvious that to correct a lean condition we need to add fuel to the mix (unless an air leak is the cause of the lean condition). But we need to add fuel carefully to address this quick, temporary, lean condition without drowning the entire carb operating range in extra fuel. A typical response is to increase the idle jet, but if you increase the idle jet larger than a size 45 or 46 you are flooding too much fuel into the transfer ports and the overall mix.
Line 450: Line 495:
  
  
-===== Links About Tuning ​& Other Notes =====+===== Additional ​Tuning Notes =====
  
-Raising ​the starting position of the needle is often suggested. This is accomplished by placing one or more #4 brass washers under the nail head of the needle in order to raise it up inside the vacuum slide. This will cause the tapered portion of the needle to become active sooner, thus richening the mid-range fuel mix. Each washer has a nominal thickness of .040-.050"​. You may want to sand or file them to a thinner thickness for even finer tuning.+**Changing ​the Needle  ​or Needle Height**
  
 Changing the needle will change the overall mid and upper-range fuel mix because the various needles have different thicknesses for the long straight portions and the tapers, plus, the angle of the taper also may vary. This thickness change will alter the cavity area of fuel flow thru the fixed needle jet, which has an ID of .114". The N65C needle (27094-88) has been found to be very effective on 1200 engines. Changing the needle will change the overall mid and upper-range fuel mix because the various needles have different thicknesses for the long straight portions and the tapers, plus, the angle of the taper also may vary. This thickness change will alter the cavity area of fuel flow thru the fixed needle jet, which has an ID of .114". The N65C needle (27094-88) has been found to be very effective on 1200 engines.
  
-  ​* **IDLE DROP METHOD** of adjusting the CV carb idle mixture screw: [[http://​xlforum.net/​forums/showthread.php?t=31262]] ((Article from XLForum member chrishajer)) +Raising the starting position of the needle is often suggested. This is accomplished by placing one or more #4 brass washers under the nail head of the needle in order to raise it up inside the vacuum slide. This will cause the tapered portion of the needle to become active sooner, thus richening the mid-range fuel mix. Each washer has a nominal thickness of .040-.050"​. You may want to sand or file them to a thinner thickness for even finer tuning. 
-  * Cantolina'​s Index List of Carb-related Threads: [[http://​xlforum.net/​forums/showthread.php?t=642408]] ((Article from XLForum member, cantolina, compiling articles from fellow members stevo, wedge, XLXR, merc, cantolina, IronMick, goldsport, chrishajer, Don Burton, gwcrim, Coolhaircut,​ Phillober , Johnny Wolf and biknut)) ​+ 
 +**Throttle Chops for Checking Cylinder Combustion** 
 + 
 +Throttle chops are used to see, on the spark plug, how the fuel is combusting in the cylinder chamber. The end of the plugs can reveal whether the combustion is burning lean (plug strap looks whitish) or properly (strap looks tan) or rich (strap looks blackish). The condition of the strap only reflects the last combustion condition in the chamber. If you idle the bike, stop it, and look at the plugs, that will ONLY demonstrate the combustion occuring at idle. 
 + 
 +The idea is to instantly stop the combustion in the chamber by '​chopping'​ the sparking which stops any further firing of the plugs. But you must also prevent the engine from continuing to rotate and pulling additional air/fuel into the chamber. Therefore, in addition to stopping the sparking, you must pull the clutch to prevent the engine from more rotation & hold the throttle position until the engine has stopped turning. Doing this will preserve the instant condition of the burn on the spark plug so it can be evaluated. 
 + 
 +**Action Description:​** To do a proper throttle chop, ride at the condition you want to evaluate, throttle open, up hill, etc. At the instant you want to evaluate, you, simultaneously,​ pull the clutch lever & flick the R/S Switch to STOP - This stops the engine - it doesn'​t fire and is not moving because the trans is disengaged. After a few seconds, when the engine has stopped rotating, you can release the throttle grip position to close the throttle plate. 
 + 
 +---------- Important ---------- > > > Let the bike DRIFT TO A FULL STOP --- before releasing the clutch lever. 
 + 
 +Turn the Keyswitch OFF & then, carefully, remove the plugs (which are now very hot). 
 + 
 +Look at the color of the plug straps to determine the burn condition - Lean (whitish), Rich (blackish) or Just Right (tan). 
 + 
 +One serious condition to look for on the plugs is speckles on the porcelain. This condition is caused by pinging (early detonation). The specks are aluminum from the pistons/​heads as the pinging causes a premature explosion in the chamber. It often is accompanied by a severe lean condition which created excessive heat. If not corrected, pinging can melt a hole in the piston. 
 + 
 +**More detailed evaluation:​** From a conversation with Wedge of the XLForum the following information has been collected and edited. 
 + 
 +In general reading the strap after an engine chop is one solid method of getting the mix correct at that particular throttle range, but more information is available to see on the plug. If you look at that strap and continue into the hollow of the plug you'll see it is connected to the outer wall of the bore. You can continue reading combustion information down that spark plug wall. 
 + 
 +Consideration should also be given to the Plug Heat Range. While the combustion event heats the heads, the plugs, being deep in the chamber, also need to transfer heat to the engine heads to be dissipated. Most plugs are in a range of relative heat ratings, from cold to average to hot variations. The rating relates to how much heat the plug holds, therefore, inversely, how much heat it passes along to the heads. So a cold plug passes heat more easily to the heads and a hot plug holds more of the heat and resists passing the heat to the heads. Various engine designs operate best with different heat rated plugs. High performance engines, which generate more heat, typically need colder plugs to pass that heat to the heads for dissipation. 
 + 
 +The internal porcelain of the spark plugs can reflect whether the heat range of the plug is correct. It is able to show how much heat is being retained by looking at the porcelain color. The correct heat range will always produce white to light tan (with light tan happening over time) porcelain. In other words a clean looking porcelain is the goal. 
 + 
 +A too cold plug (which retains too little heat) will cause the porcelain to go gray because the deposits are not being consumed with enough heat to burn them away. That gray will be darker as the plug heat range gets too far (colder) from what the engine wants. Eventually it will become black but not a burnt black, just black discoloration and even powdery looking or in a worst case scenario, a wet black from unburned fuel. 
 + 
 +A too hot plug (which retains too much heat) will start to show itself as darker tan, leading into dark brown, leading to black, leading into blistered black or dark brown. 
 + 
 +This NGK link, related to their spark plugs, may be of interest: https://​ngksparkplugs.com/​en/​resources/​spark-plug-basics 
 + 
 +\\ 
 + 
 + 
 +===== Links About Tuning & Other Notes ===== 
 + 
 +**LINKS** 
 + 
 +  ​* **IDLE DROP METHOD** of adjusting the CV carb idle mixture screw: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​18838-the-idle-drop-method-of-adjusting-the-cv-carb-idle-mixture?t=31262]] ((Article from XLForum member chrishajer)) 
 +  * Cantolina'​s Index List of Carb-related Threads: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​84713-all-things-carburetor-tuning-jetting-how-to-sticky-index?t=642408]] ((Article from XLForum member, cantolina, compiling articles from fellow members stevo, wedge, XLXR, merc, cantolina, IronMick, goldsport, chrishajer, Don Burton, gwcrim, Coolhaircut,​ Phillober , Johnny Wolf and biknut)) ​
 The Three Top Sticky Threads (in the order Cantolina has them): The Three Top Sticky Threads (in the order Cantolina has them):
-  * **Read this First - Jetting 101**: [[http://​xlforum.net/​forums/showthread.php?t=49078]] ((Article from XLForum member Stevo)) +  * **Read this First - Jetting 101**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​29446-read-this-first-jetting-101?t=49078]] ((Article from XLForum member Stevo)) 
-  * **PLUG READING 101**: [[http://​xlforum.net/​forums/showthread.php?t=920271]] ((Article from XLForum member Wedge)) +  * **PLUG READING 101**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​104264-plug-reading-101?t=920271]] ((Article from XLForum member Wedge)) 
-  * **Carb basics and jetting by reading the plugs**: [[http://​xlforum.net/​forums/showthread.php?t=506958]] ((Article from XLForum member XLXR)) +  * **Carb basics and jetting by reading the plugs**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​73013-carb-basics-and-jetting-by-reading-the-plugs?t=506958]] ((Article from XLForum member XLXR)) 
-  * **Discussing Joe Minton Article about CV40 carb tuning**: [[http://​xlforum.net/​forums/showthread.php?​t=1091101]] +  * **Discussing Joe Minton Article about CV40 carb tuning**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​114343-by-the-numbers-american-iron-magazine?​t=1091101]] 
-  * **Carburetor Sticky Index on XLForum**: [[http://​xlforum.net/​forums/showthread.php?​t=642408]] +  * **Carburetor Sticky Index on XLForum**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​84713-all-things-carburetor-tuning-jetting-how-to-sticky-index?​t=642408]] 
-  * **CV Needle Drawings and Database**: [[http://​xlforum.net/​forums/showthread.php?t=165259]]+  * **CV Needle Drawings and Database**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​46008-cv-needle-drawings-and-database?t=165259]]
  
   * Post a thread of your own on XLForum.net with your information from above and ask for help in tuning your particular engine/carb combination   * Post a thread of your own on XLForum.net with your information from above and ask for help in tuning your particular engine/carb combination
-  * **Provide This Info When Asking About Tuning Carb'd Models**: [[http://​xlforum.net/​forums/showthread.php?​t=1924896]]+  * **Provide This Info When Asking About Tuning Carb'd Models**: [[https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​179137-provide-this-info-when-asking-about-tuning-carb-d-models?​t=1924896]]
  
 Sub-Documents Sub-Documents
Line 477: Line 561:
  
 ==== Other Engine Checks ==== ==== Other Engine Checks ====
-  * Check engine compression - Keep record for later comparison ​Preferred Minimum 883=120psi - 1200=150psi+  * Check engine compression - Keep record for later comparison 
 +    * Preferred Minimum883=120psi - 1200=150psi ​- 2004+ 1200=180psi
     * Warm up engine - Try a 10-15 minute ride - let engine cool just enough to touch     * Warm up engine - Try a 10-15 minute ride - let engine cool just enough to touch
     * Remove Spark Plugs & Air Cleaner - Connect gauge to Front Cylinder     * Remove Spark Plugs & Air Cleaner - Connect gauge to Front Cylinder
Line 505: Line 590:
 Insert the carb, attach the carb mounting bracket (which you are now confident will not distort the carb-to-manifold positioning),​ and bolt it all in place. Insert the carb, attach the carb mounting bracket (which you are now confident will not distort the carb-to-manifold positioning),​ and bolt it all in place.
  
-((http://​xlforum.net/​forums/showthread.php?​postid=5342857#​post5342857))+((https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-era-specific-and-model-specific/​frame-mount-evo-sportster-talk-1986-2003-models/​181911-carb-questions?​postid=5342857#​post3887561))
  
 \\ \\
  
-===== Accelerator Pump and Fuel Float Bowl =====+===== Accelerator Pump =====
  
 The Accelerator Pump (AP) is part of the Transfer function of the carburetor, providing additional fuel when the carb transitions from the Idle operation up to the acceleration and/or cruising operation. The Accelerator Pump (AP) is part of the Transfer function of the carburetor, providing additional fuel when the carb transitions from the Idle operation up to the acceleration and/or cruising operation.
Line 527: Line 612:
 | 1989-1990 | 27159-89 | 27160-89 | 27577-88 | ::: | | 1989-1990 | 27159-89 | 27160-89 | 27577-88 | ::: |
 | 1991 | 27159-89A | 27160-89 | 27577-88 | ::: | | 1991 | 27159-89A | 27160-89 | 27577-88 | ::: |
-| 1992-2003 | 27159-92 | 27160-89 | 27577-92 | ::: |+| 1992-2003 ​- 883/1200\\ . . . . Except 1200S | 27159-92 ​| 27160-89 | 27577-92 | ::: | 
 +| 1998-2003 - 1200S | 27380-98 ​| 27160-89 | 27577-92 | ::: |
 | 2004-2006 - 883 | 27777-04 | 27260-00 | 27577-92 | ::: | | 2004-2006 - 883 | 27777-04 | 27260-00 | 27577-92 | ::: |
 | 2004-2006 - 1200 | 27256-01 | 27260-00 | 27577-92 | ::: | | 2004-2006 - 1200 | 27256-01 | 27260-00 | 27577-92 | ::: |
-{{:​techtalk:​evo:​carb:​cv40-floatbowl-0304-ap.jpg?​600|}} ((Discussion & pics from Robistro on the XLForum at http://​xlforum.net/​forums/showthread.php?​t=2070191)) \\ +{{:​techtalk:​evo:​carb:​cv40-floatbowl-0304-ap.jpg?​600|}} ((Discussion & pics from Robistro on the XLForum at https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​194022-cv-carb-float-bowl-accel-pump-2-models-id?​t=2070191)) \\ 
  
-{{:​techtalk:​evo:​carb:​xl1200s_keihin_cv_float_bowl_-_49_state_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) \\+{{:​techtalk:​evo:​carb:​xl1200s_keihin_cv_float_bowl_-_49_state_by_hippysmack.jpg?​direct&​300|}} ((photo by Hippysmack)) ​| Float Bowl P/N 27380-98 was used on\\ all 1998-2003 US version 1200S models.\\ These have no overflow tubes.\\ < < < --------------------------------------------- \\ \\ \\ \\  --------------------------------------------- > > >  \\ Float Bowl P/N 27256-01, which has\\ an overflow tube, was used on the\\ 2001-2003 International version 1200S\\ models as well as every version 1200\\ model made from 2004-2006.| {{:​techtalk:​evo:​carb:​cv40-floatbowl-05-close.jpg?​direct&​220|}} ((pic from BestCoastXL of the XLForum https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-motor-engine/​sportster-motorcycle-engine-conversions/​201980-hammer-1275-clang-noise-slow-oil-feed-kinked-crankcase-vent?​t=2079110+post#​943)) |
  
-There are 3 types of flow checks (on different versions of the CV40) for the accelerator pump jetsball, needle and calibrated orifice-(no check at all). ((buster of the XLFORUM http://​xlforum.net/​forums/showthread.php?t=2024981))((Older units had change-able jets to calibrate the squirt, newer ones are fixed and can only adjust the timing of the squirt.)) \\+{{techtalk:evo:​carb:​cv40-accelpump-ckvalve.jpg|}} ​((Annotated by IXL2Relax ​at the XLForum))\\ 
 + 
 +{{:​techtalk:​evo:​carb:​91_keihin_cv_accelerator_pump_jet_by_blackbikedave.jpg?​direct&​400|}} ​((photos by BlackBikeDave,​ cropped-annotated by Hippysmack https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​189871-1991-cv-carb-accelerator-pump-nozzle-cleaning?​t=2024981)) \\
  
-{{techtalk:​evo:​carb:​cv40-accelpump-ckvalve.jpg |Annotated by IXL2Relax at the XLForum}} 
  
 \\ \\
  
-{{:​techtalk:​evo:​carb:​91_keihin_cv_accelerator_pump_jet_by_blackbikedave.jpg?​direct&400|}} ((photos by BlackBikeDave,​ cropped-annotated by Hippysmack http://​xlforum.net/​forums/​showthread.php?​t=2024981)) \\+===== Fuel Float Float Bowl Drain =====
  
-**Fuel Float Hinge Pin CAUTION!** - Be very careful removing the hinge pin on which the fuel float operates. The pin should ONLY be REMOVED in one direction ​the direction as shown by an arrow embossed in the carb bodyTo REINSERT the pin, press it into place in the opposite direction ​from the embossed arrowBe careful not to stress or break the mounting posts nor twist & damage ​the float arms.+{{:​techtalk:​evo:​carb:​cv40-float-info.jpg?​300|}}((Pic ​from Cantolina of the XLForum https://www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​9621-carb-adjusting-where-are-the-jets-and-the-mixture-screw?​t=14949 - Annotated by IXL2Relax)){{:​techtalk:​evo:​carb:​cv40-floatbowl-drainscrew.jpg?​300|}}((Annotated by IXL2Relax))
  
-**Float Bowl Overflow** ​Notice ​the Overflow Tube on the bottom of the float bowl, in the [[techtalk:​evo:​carb02#​working_with_cv40_carburetors|above picture]]. The channel used for the escaping overflow fuel was also used for a float bowl drain. The overflow was a safeguard against the failure of the float bowl valve from not closing. Should that happen, the fuel would be expelled onto the ground rather than being pushed into the intake manifold and filling the cylinders (and eventually the crankcase) with raw fuel.+The fuel float is created by a hollow plastic chamber. It moves on a hinge pin mounted to the carb body. It incorporates a TANG (metal tab) that operates the Float Valve. By adjusting the tang in micro-movements, it can raise or lower the fuel level that is maintained in the carb float bowl. See the adjustment specification & procedure ​[[techtalk:​evo:​carb02#​setting_the_float_level|earlier in this page]].
  
-Note, however, that the 1998-2003 1200S carbs have no float bowl overflow tube protection. They also have no drain plug & hose to empty float chamber for off riding season or extended storage.+**Fuel Float Hinge Pin - CAUTION!** - Be very careful removing the hinge pin on which the fuel float operates. The pin is designed to ONLY be REMOVED in one direction - the direction as shown by an arrow embossed in the carb body. To REINSERT the pin, press it into place in the opposite direction from the embossed arrow. Be careful not to stress or break the mounting posts nor twist & damage the float arms. (Wedge of the XLForum has suggested carefully drilling both posts to barely allow the pin to move freely in the posts since the float bowl, when on, will prevent the pin from escaping the posts.) 
 + 
 +**Float Bowl Drain** - Notice the Drain Tube on the bottom of the float bowl. The same channel that is used to allow the overflow fuel to escape (as a precaution) is also used for a float bowl drain. ​ The drain screw allowed for emptying the bowl of fuel when the carb was being serviced or when the bike was put into storage or unused for an extended period of time. The overflow tube (as shown in previous pictures) was a safeguard against the failure of the float bowl valve from not closing. Should that happen, the fuel would be expelled onto the ground rather than being pushed into the intake manifold and filling the cylinders (and eventually the crankcase) with raw fuel. 
 + 
 +Note, however, that the 1998-2003 1200S carbs (US Version) ​have no overflow drain screw, nor do they have the float bowl overflow tube protection.
  
  
Line 576: Line 667:
 {{:​techtalk:​evo:​carb:​cv40-enrichener-assy.jpg|}}((Pics from Phillober t=848307\\ & gm1ll t=1553245))((Annotated by IXL2Relax at the XLForum)) {{:​techtalk:​evo:​carb:​cv40-enrichener-assy.jpg|}}((Pics from Phillober t=848307\\ & gm1ll t=1553245))((Annotated by IXL2Relax at the XLForum))
  
-An XLForum Thread ​showing ​the replacement of the cable is here: http://​xlforum.net/​forums/showthread.php?t=848307 +An XLForum Thread ​discussing ​the replacement of the cable is here (but pics are missing)https://www.xlforum.net/​forum/sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​99252-replacing-the-choke-knob-enrichener-cable-with-pics?t=848307
 \\ \\
  
Line 587: Line 677:
 Reversion is created in the engine combustion cycle by the relationship between the cams and the exhaust system. Specifically,​ between the harmonic waves created in the exhaust pipes and the overlap of the exhaust valve about to close while the intake valve is already opening. This overlap period, where both valves are open at the same time, is usually extended in high lift cams, causing the exhaust system to have a great affect on the cylinder fill operation. The exhaust functioning can have a positive or negative affect. Reversion is created in the engine combustion cycle by the relationship between the cams and the exhaust system. Specifically,​ between the harmonic waves created in the exhaust pipes and the overlap of the exhaust valve about to close while the intake valve is already opening. This overlap period, where both valves are open at the same time, is usually extended in high lift cams, causing the exhaust system to have a great affect on the cylinder fill operation. The exhaust functioning can have a positive or negative affect.
  
-If/when reversion is occuring, the intake charge ends up passing through the carb three times: pulled in, pushed out, and pulled back in again. Each time it is picking up fuel making the mixture richer. ((Based on info from Aaron Wilson from the XLForum (aswracing) - http://​xlforum.net/​vbportal/forums/showthread.php?t=1028905 - Post#12))+If/when reversion is occuring, the intake charge ends up passing through the carb three times: pulled in, pushed out, and pulled back in again. Each time it is picking up fuel making the mixture richer. ((Based on info from Aaron Wilson from the XLForum (aswracing) - https://www.xlforum.net/​forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/​sportster-motorcycle-motor-top-end/​110036-s1-lightning-heads?t=1028905 - Post#15))
  
 You can read more in the REF Section on [[techtalk:​evo:​carb04#​exhaust_pipes_cams_-_power_or_reversion|Exhaust Pipes & Cams - Power or Reversion.]] ​ You can read more in the REF Section on [[techtalk:​evo:​carb04#​exhaust_pipes_cams_-_power_or_reversion|Exhaust Pipes & Cams - Power or Reversion.]] ​
  
 ====== More on Jetting ====== ====== More on Jetting ======
-Differences in pilot jets. \\ 
-{{:​techtalk:​evo:​carb:​pilot_jet_chart_by_rocketmangb.png?​direct&​600|}} ((drawing by rocketmangb of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1710330)) \\ 
  
  
 +
 +Differences in pilot jets. \\
 +
 +See the Charts Here: [[techtalk:​evo:​carb01#​slow_main_jets_-_p_n_comparisons|techtalk:​evo:​carb01#​slow_main_jets_-_p_n_comparisons]]
  
 \\ \\
  
 +{{:​techtalk:​evo:​carb:​pilot_jet_chart_by_rocketmangb.png?​direct&​600|}} ((drawing by rocketmangb of the XLFORUM https://​www.xlforum.net/​forum/​sportster-motorcycle-forum/​sportster-motorcycle-intake-and-exhaust/​sportster-motorcycle-air-intake-carburetor-efi-fuel-and-exhaust/​159523-cv-carb-pilot-jet-advice-afr?​t=1710330)) \\
 +
 +\\
  
 \\ \\
 [[:​techtalk:​menu|{{:​techtalk:​gototechnicalmenu.jpg|}}]] [[:​techtalk:​menu|{{:​techtalk:​gototechnicalmenu.jpg|}}]]