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techtalk:ih:carb01r [2019/10/10 16:08]
hippysmack [Idle Speed Adjustment]
techtalk:ih:carb01r [2019/11/14 05:04] (current)
hippysmack [79 and later 34mm Keihin butterfly carbs]
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 {{:​techtalk:​ih:​carb:​keihin_buttefly_ac_side_functions_by_spuggy_-_annotated_by_hippysmack.jpg?​direct&​300|}} ((photo by spuggy of the XLFORUM, annotated by Hippysmack http://​xlforum.net/​forums/​showthread.php?​p=5694195&​highlight=keihin#​post5694195)) {{:​techtalk:​ih:​carb:​keihin_buttefly_ac_side_functions_by_spuggy_-_annotated_by_hippysmack.jpg?​direct&​300|}} ((photo by spuggy of the XLFORUM, annotated by Hippysmack http://​xlforum.net/​forums/​showthread.php?​p=5694195&​highlight=keihin#​post5694195))
- 
-====== Service Bulletin Information ====== 
  
  
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 The idle mixture screw is held in place by a spring on top of the carburetor near the intake mounting flange on all models. \\ The idle mixture screw is held in place by a spring on top of the carburetor near the intake mounting flange on all models. \\
-  * On 76-78 carbs, the screw and it's spring is sticking up in plain site. +  * On 76-78 carbs, the screw and it's spring is sticking up in plain site. \\ 76 carbs didn't come with a seal on the mixture screw. It was added thru a service bulletin in December of 1976. ((HD TSB #M707 dated December 1, 1976)) \\ The ID of the seal (27355-76) was a little small and it was suggested to enlarge the hole slightly for the screw. \\ It was to be placed between the spring and the carb body. This still leaves the spring being able to cut the seal
-  * On 79 carbs, the screw is inside a towered boss under a limiter cap. \\ The limiter cap can be removed to adjust the mixture screw. However, with the cap on, the mix can still be adjusted with the limits of the cap.+  * On 79 carbs, the screw is inside a towered boss under a limiter cap. \\ The limiter cap can be removed to adjust the mixture screw. However, with the cap on, the mix can still be adjusted with the limits of the cap. \\ A washer between the seal (O-ring) and the spring was added in 79 to protect the rubber O-ring from damage from the spring.
   * On 80-up carbs, the screw is inside a towered boss under a (non removable) plug. \\ The plug can be removed by drilling a small hole through it and using a small screwdriver to pop it out. \\ Wrap a piece of tape around the drill bit as a guide so you won't drill into the mixture screw.   * On 80-up carbs, the screw is inside a towered boss under a (non removable) plug. \\ The plug can be removed by drilling a small hole through it and using a small screwdriver to pop it out. \\ Wrap a piece of tape around the drill bit as a guide so you won't drill into the mixture screw.
  
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 |{{:​techtalk:​ih:​carb:​keihin_butterfly_carb_2_by_hopper.jpg?​direct&​300|}}| |{{:​techtalk:​ih:​carb:​keihin_butterfly_carb_2_by_hopper.jpg?​direct&​300|}}|
  
 +==== Choke Shaft and Plastic Parts (76-E78) ====
 +
 +Kits were available from the MoCo for 76-78 FX & FL carbs to adapt for a fast idle cam. It was also available as a replacement for 79-up carbs. \\
 +The Choke Shaft Kit is (27045-78) and the Plastic Parts kit (27046-78) as shown below (with the parts list including 3 springs, 2 clips and 2 washers). \\
 +{{:​techtalk:​ih:​carb:​keihin_choke_shaft_kit_27045-78.jpg?​direct&​300|}} {{:​techtalk:​ih:​carb:​keihin_plastic_parts_kit_27046-78.jpg?​direct&​300|}} \\
 +The ball under the choke lever drive must ride in the detents on the bottom of the choke lever drive. \\
 ==== Fast Idle Cam (79-up) ==== ==== Fast Idle Cam (79-up) ====
  
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 All year Keihin jet locations: \\ All year Keihin jet locations: \\
 {{:​techtalk:​ih:​carb:​keihin_10_by_county_fair.jpg?​direct&​300|}} ((photo by County Fair of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​s=9e387afdd8bddbd4444d18324d2d215c&​t=1760294&​page=3)) \\ {{:​techtalk:​ih:​carb:​keihin_10_by_county_fair.jpg?​direct&​300|}} ((photo by County Fair of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​s=9e387afdd8bddbd4444d18324d2d215c&​t=1760294&​page=3)) \\
 +
 +===== Installing an Adjustable Main Jet (L76-87) =====
 +There is an adjustable main jet available from J&P Cycles or others. \\
 +These work great and you don't have to fool around jet guessing whether you have the right size main jet or not. \\
 +They are simple to adjust. Just wind it up to about 65 MPH and run it in until it misses and back it out about a full turn. ((oldnavy of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=877868&​page=2)) \\ 
 +
 +This kit can be purchased online. It comes with an installation guide and index pointer. \\
 +The tool marks inside of the float bowl (as installed) for drilling the proper sized hole to thread in the adjustable main jet.\\
 +The kit can be purchased online. \\
 +PDF instructions - [[http://​www.vtwinmfg.com/​instructions/​35/​35-0369.pdf]] \\
 +{{:​techtalk:​ref:​carb:​keihin_butterfly_adjustable_main_jet_35-0369.jpg?​direct&​300|}} \\
 +
 +This replaces the main jet (has to be removed). \\
 +The float bowl has to be removed to install the adjustable main jet. \\
 +A guide tool is included with the kit to install the new jet to properly index the carburetor float bowl. \\
 +A index pointer is installed in the guide, bowl reinstalled and the pointer is pushed down from inside the venture to dimple the bowl. \\
 +The bowl is once again removed and a 1/​16"​-1/​8"​ pilot hole is drilled followed by a 15/64" bit. \\
 +After checking for burrs, removing the index tool and guide and cleaning up, the adjustable jet is installed in the float bowl. \\
 +(partially unscrew the small '​T'​ handle so that the needle in the adjustable jet is not exposed to accidental damage) \\
 +Remove the nut from the adjustable jet, insert the jet through the 15/64" hole drilled earlier. \\
 +Then re-tighten the bowl and gently screw in the '​T'​ handle to the needle seat and then back it out 4 turns. \\
 +Finer tuning can be achieved by reading the spark plugs and small adjustments to the “T” handle. \\
 +This adjustable jet eliminates the chore of carrying and continually changing different main jets with every change in exhaust system or air cleaner. \\
 +The hole in the bowl for the '​T'​ handle jet has to be indexed correctly in order for this to work. \\
 +The adjustable main jet is designed to operate in conjunction with a 1.80 main jet included with the kit. \\
 +Make sure you record or remember the number of turns off the seat and back off the '​T'​ handle before removing the float bowl later. \\
 +This will help prevent needle / jet interference when the float bowl is reinstalled. \\
 +For initial adjustment (standard pipes and A/C) it's recommended that the adjustment needle be backed out four (4) turns from the seat.
 +The adjustable jet set screw is turned in, towards the float bowl to lean the fuel/air mixture and out from the float bowl to richen the mixture. \\
 +Check plugs frequently after jet adjustment, exhaust or A/C to avoid too lean or too rich conditions. \\
 +
 +|{{:​techtalk:​ref:​carb:​kehien_butterfly_carb_1_by_leucadiaguit_-_cropped.jpg?​direct&​300|}}|{{:​techtalk:​ref:​carb:​kehien_butterfly_carb_2_by_leucadiaguit_-_cropped.jpg?​direct&​300|}}|
 +
  
 ====== ​ Accelerator Pump System ====== ====== ​ Accelerator Pump System ======
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 Any wiring that that may get too hot / catch fire doesn'​t need gas nearby. \\ Any wiring that that may get too hot / catch fire doesn'​t need gas nearby. \\
  
-While installing ​the accelerator ​pumpthe diaphragm goes on first, then spring, then cover. \\ +|After adjusting. ((photo by Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=276157&​page=3))|Accelerator ​pump from the outside. \\ (see caution above) ((photo by Hopper of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=276157&​page=3))| 
-Make sure those two square section O-rings are in place and in good conditionElse, gas will leak out there instead of getting squirted into your engine\\+|{{:​techtalk:​ih:​carb:​keihin_butterfly_carb_15_by_hopper.jpg?​direct&​300|}}|{{:​techtalk:​ih:​carb:​keihin_butterfly_carb_16_by_hopper.jpg?​direct&​300|}}|
  
-|After adjusting. ((photo by Hopper ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=276157&​page=3))|Accelerator ​pump from the outside. \\ (see caution above) ((photo by Hopper ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=276157&page=3))|Check position ​of O-rings. ((photo by Hopper ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=276157&page=3))| +===== Andrews High Flow Accelerator Pump (Keihin butterfly) ===== 
-|{{:​techtalk:​ih:carb:keihin_butterfly_carb_15_by_hopper.jpg?​direct&​300|}}|{{:​techtalk:​ih:carb:keihin_butterfly_carb_16_by_hopper.jpg?​direct&​300|}}|{{:​techtalk:​ih:carb:keihin_butterfly_carb_17_by_hopper.jpg?​direct&​300|}}|+ 
 +79-up 34mm Keihin carbs will not fill there accelerator pumps as quickly as the 76-78 38mm ones. ((Joe Minton Article "​Tuning HD's Keihin Carburetors"​)) \\ 
 +The earlier pump would refill in about 1/2 second. The later one takes three seconds. \\ 
 +The earlier pump will allow you to get by the choke and will help you catch the engine if you let the clutch out too fast at a red light. \\ 
 +The main difference is the pump housing. The early accel pump passages had both an inlet and an outlet hole for gas routing. \\ 
 +The Andrews pump is reportedly the same as Harley part (27364-76) for the early 38mm Keihins. \\ 
 +Actually, if you can find a 38mm pump and drill the hole in your carb body, you'll have the old style accel pump. \\ 
 + 
 +On 1980-1988 Keihin carbs, the stock accelerator pump is restricted by eliminating the check valves in the pump. A high flow accelerator pump puts them back. ((IronMick ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=93242)) \\ 
 +The result is increased fuel flow through the pump and greatly improved low end and mid range throttle response. \\ 
 + 
 +The Keihin butterfly carb already has an accelerator pump, so the Andrews high-flow pump body just replaces the stock one on the bottom of the float bowl. ((83XLX of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2064358)) \\ 
 +There is one on the [[https://​vtwin.parts/​index.php?​_route_=supplier/​v-twin/​sportster-1952-up/​fuel-air-system/​carburetor/​rebuild-kits/​harley-davidson-indian-motorcycle-keihin-carburetor-accelerator-pump-kit-35-9050&​limit=50|V-twin website]] called the Flowmaster accelerator ​pump. \\ 
 +It has a V-twin part number of 35-9050, Manufacturer Keihin, Part Number: 269050. \\ 
 +//​Flowmaster carb accelerator pump kit improves throttle response on Keihin carburetor models with a greater volume of fuel from the pump circuit//. \\ 
 +Makes since as Andrews used to make the Flowmaster carb. \\ 
 +The pump is listed as out of stock and has been since at least of march 2018 yet the listing is still up. \\ 
 +In fact and according to the V-twin website, it's been discontinued and no replacement is listed. \\ 
 + 
 +Installation instructions from Andrews is [[http://​www.andrewsproducts.com/​files/​assets/​carbpump1.pdf|here]]. \\ 
 + 
 +Features: ​((http://​www.johnnysreplacementparts.com/​product/​andrews-high-flow-accelerator-pump-kit-269050/​)) \\ 
 +  * Improves throttle response 
 +  * Larger fuel volume/​discharge 
 +  * Fits 79-89 H-D using Keihin carburetor ​(except Flowmaster and CV carbs) 
 +  * Easy to install 
 +  * Fits 79-89 H-D with Keihin carb 
 +  * Dimensions: 5"​x3"​x1";​ 0.3 pounds 
 + 
 +A high flow accelerator pump is also a great all around upgrade for these carbs. ​((oldnavy ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=877868&page=2)) \\ 
 +{{:​techtalk:​ref:​carb:​andrews_accel_pump_1_by_paraord.jpg?​direct&​300|}} ((photo by paraord ​of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=3908971)) {{:​techtalk:​ref:​carb:​andrews_accel_pump_2_by_paraord.jpg?​direct&​300|}} ((photo by paraord of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​p=3908971)) \\ 
 + 
 +**How the High Flow Accelerator Pump should be installed**:​ ((Andrews Products, Inc. INSTALLATION INSTRUCTIONS 
 +High Flow Accelerator Pump for Stock Keihin Carburetors For Stock Keihin Carbs from 1980-1988)) \\ 
 +  - Remove float bowl from carburetorThere are four screws holding it in place. \\ It is not necessary to remove the entire carburetor from the engine to install your new high flow accelerator pump. 
 +  - Clean any fuel residue from the bowl assembly and remove the stock accelerator pump housing. \\ It is held in place with three screws but one of them already has been removed with the bowl.  
 +  - Position the bowl upside down for drilling a single hole through the bottom. 
 +  - Any drill of approximately 1/16 diameter will be quite satisfactory. \\ The exact location for this hole is already marked with a dimple on the bottom of the float bowl casting as shown in photo below. \\ {{:​techtalk:​ref:​carb:​keihin_butterfly_carb5.2_by_brendan_-_annotated.jpg?​direct&​300|}} ​((photo by brendan ​of the XLFORUM, annotated by Hippysmack ​http://​xlforum.net/​forums/​showthread.php?​p=5759323&highlight=keihin+butterfly#​post5759323)) 
 +  - Feed the drill through until it breaks out into the float chamber. \\ Don’t worry if the hole breaks into either a cross drilled passage or through the actual bottom of the bowl. \\ The location is not critical as long as fuel can feed through into the accelerator pump. 
 +  - Thoroughly clean any drill chips from the bowl. There is a small bypass hole in the bottom of the bowl which does not have to be plugged. \\ Several earlier magazine articles have recommended plugging this hole but there will be no measurable benefit from doing so. 
 +  - Install the new accelerator pump housing onto the bowl with the two shortest screws of the original three. \\ Make sure that the two small O-ring seals are installed; \\ One into a recess in the pump housing. \\ The second into a recess into the bottom of the bowl casting. 
 +  - If the accelerator pump jet needs to aimed differently,​ now is the time to do this. \\ With a small adjustable wrench, carefully reposition the pump jet by gently turning it in the bowl casting (it’s a press fit). 
 +  - Reinstall the bowl and pump assembly back onto the carburetor body to complete the job. \\ The extra fuel from the larger capacity pump should result in smoother, quicker throttle response especially off idle or at low RPM. 
 + 
 +===== Alternative using CV accelerator pump ===== 
 + 
 +It looks like Keihin made all these covers so any of the basic raw castings can have additional operations incorporated to be used in any of their many configurations. ((chevelle of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2009248)) \\  
 +The stock pump cover for non CV Harley carbs (2-2) uses the same passage for supply and pump shot. \\ 
 +The high flow cover uses separate passages for supply and pump shot (4-2). \\ 
 +It also contains a loose check ball in the passage. \\ 
 +The stock cover is not easily owner modified to incorporate separate passages and check ball (2-2). \\ 
 + 
 +The Keihin CV pump cover (4-1) (left in center photo) is a high flow cover just as the Andrews. \\ 
 +The only difference is the (4-1) cover has an extra counter-bore compared with stock non CV. \\ 
 +The CV cover is made with packing bore in cover. \\ 
 +The non CV is made with packing bore in bowl body. \\ 
 +It seems the CV (4-1) cover can be made to work in a non CV if (2) square packing are used, one in cover and one in carb body. \\ 
 +Note: All orifices in covers are the same. \\ 
 + 
 +{{:​techtalk:​ref:carb:acel_pumps_1_by_chevelle.jpg?​direct&​300|}} ​((photo by chevelle of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2009248)) ​{{:​techtalk:​ref:carb:acel_pumps_2_by_chevelle.jpg?​direct&​300|}} ​((photo by chevelle of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2009248)) ​{{:​techtalk:​ref:carb:acel_pumps_3_by_chevelle.jpg?​direct&​300|}} ​((photo by chevelle of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2009248)) \\
  
 ====== Float Level Adjustment ====== ====== Float Level Adjustment ======
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 ====== Heat Spacer ====== ====== Heat Spacer ======
 **The insulating block was never suggested for use on Sportster Keihin butterfly carbs by the MoCo**. \\ **The insulating block was never suggested for use on Sportster Keihin butterfly carbs by the MoCo**. \\
 +In December of 1976, insulating block (27412-57) was suggested to use on 76 and later FL and FX models (one block on FX and two blocks on FL models). ((HD TSB #M707 dated December 1, 1976)) \\
 In August of 1977, a Service Bulletin was issued regarding the use of a spacer block on 1977→ 1200CC engines. ((HD TSB #M715 dated August 12, 1977)) \\ In August of 1977, a Service Bulletin was issued regarding the use of a spacer block on 1977→ 1200CC engines. ((HD TSB #M715 dated August 12, 1977)) \\
 In that, it is suggested to install a 'new available'​ spacer block (5895) on 1200CC engines between the intake manifold and the carburetor. \\ In that, it is suggested to install a 'new available'​ spacer block (5895) on 1200CC engines between the intake manifold and the carburetor. \\
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 Most carburetor problems really are electrical, just like the old timers always say. (Hopper) Most carburetor problems really are electrical, just like the old timers always say. (Hopper)
  
 +===== Altitude and Ambient Temps =====
 +A Carb works by mixing air and fuel into a vaporous mixture. We want the ideal mixture so the bike runs well. ((stevo of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=49078)) \\
 +Unfortunately it's not quite simple as a carburetor mixes air by a set volume to set the amount of fuel. \\
 +The amount of oxygen density in that set amount of air varies and this is what gives variations in mixture due to differing conditions. \\
 +The required air / fuel mixture changes depending on the conditions. \\
 +Max power for acceleration is around 12.5 parts air to one part fuel. \\
 +Chemically correct or stoichiometric is 14.7:1 \\
 +A rich mixture misfire usually needs about 6-7:1 \\
 +A lean mixture misfire usually needs over 20:1 \\
 +We want to try and get the most fuel in there that we can but the limiting factor is the amount of oxygen that we can fit in there and give the correct ratio. \\
 +A number of things have an effect on the amount of oxygen we can get in there. \\
 +Just like you run out of breath at altitude because of lack of oxygen, so does your bike. \\
 +
 +  * Carburetor modification kits (including jet(s) and an accelerator pump stop screw) were made available for 1200cc, 1340cc and 1000cc models to provide leaner fuel mixtures when operating at elevations above 4000 feet sea level. ((HD Service Blletin #M-730 dated June 15, 1978))
 +    * Normally, leaner fuel/air mixtures are required for proper engine operation as the elevation above sea level increases. The decreased jet sizes and accelerator pump modifications should be installed where there is evidence of a rich condition causing loss of smooth combustion, stumbling on acceleration or such other carburetor issues at high altitudes. ​
 +    * High Altitude Kits:
 +      * 1978 1/2 FLH-1200 (27094-78). \\ Consisted of a 160 main jet, 72 slow jet and a label for the downtube. \\ In addition to installing the parts on the carb, the FLH-1200 models required changing the position of the accelerator pump spring pre-load position. \\ The spring should go in the top (#1) position as opposed to the #3 (std) position on the pump lever.
 +      * FX/​FXE/​FXS-1200 (27095-78). \\ Consisted of an accelerator pump screw and a label for the downtube. \\ Install and adjust the accel pump stop screw to extend 1/8" past hole in lever.
 +      * XLH/​XLCH/​XLCR-1000 (27096-79). \\ Consisted of a 160 main jet, an accelerator pump screw and a label for the downtube. \\ Install and adjust the accel pump stop screw to extend 1/8" past hole in lever.
 +      * FLH-80, 1340cc, (27093-78). \\ Consisted of a 155 main jet and a label for the downtube.
 +
 +**Note**, any motorcycle modified for high altitude operation must be converted back to standard if operated at altitudes below 4000 feet. \\ An overly lean condition can cause engine damage.
 +
 +The air pressure or barometric pressure is higher at sea level than at high altitude. \\
 +The more pressure we have means the more oxygen in the same amount of air. \\
 +Example: \\
 +The bike is jetted for the correct mixture at sea level. Then you go up the mountains. \\
 +The higher the altitude, the less oxygen, and the richer the bike will run. \\
 +The opposite is also true. \\
 +
 +Hotter Air = Less Oxygen → Richer Mix ((stevo of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=49078)) \\
 +Colder Air = More Oxygen → Leaner Mix \\
 +Higher Barometric Pressure (Low Altitude) = More Oxygen → Leaner Mix \\
 +Lower Barometric Pressure (Higher Altitude) = Less Oxygen → Richer Mix \\
 +Higher Humidity = Less Oxygen → Richer Mix \\
 +Lower Humidity = More Oxygen → Leaner Mix \\
 ===== Fuel overflow ===== ===== Fuel overflow =====
 The overflow tube is a safety feature in case the float needle does not prevent flow and the bowl gets full. ((IXL2Relax of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2071025)) \\ The overflow tube is a safety feature in case the float needle does not prevent flow and the bowl gets full. ((IXL2Relax of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=2071025)) \\
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 ====== Helpful Links ====== ====== Helpful Links ======
 **Video**: \\ **Video**: \\
-Here are some excellent videos of servicing the pre-CV Keihin Butterfly carbs:​((Used by permission - SportsterPavel ​at the XLForum - http://​xlforum.net/​forums/​showthread.php?​t=2055701))+Here are some excellent videos of servicing the pre-CV Keihin Butterfly carbs: ((Used by permission - SportsterPaul ​at the XLForum - http://​xlforum.net/​forums/​showthread.php?​t=2055701))
  
   * [[https://​youtu.be/​f_Ek37GEEN4|#​1 - Tips and tricks.]]\\   * [[https://​youtu.be/​f_Ek37GEEN4|#​1 - Tips and tricks.]]\\