Differences

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

--- techtalk:ih:carb01r [2020/04/01 20:08]
hippysmack [IH: Carburetor, Intake Manifold & Exhaust - Sub-01R]
+++ techtalk:ih:carb01r [2023/12/29 21:29]
hippysmack
@@ Line 1: / Line 1: @@
 [[:techtalk:menu|{{  :techtalk:gototechnicalmenu.jpg|}}]]
-====== IH: Carburetor, Intake Manifold & Exhaust Systems - Sub-01R ======
+====== IH: Carburetor, Intake Manifold & Exhaust - Sub-01R ======
 ====== Keihin Butterfly Carb (non CV) Functions, Adjustments, Tuning ======
@@ Line 7: / Line 7: @@
   * [[techtalk:ih:carb01q|Rebuilding the Keihin Butterfly Carb]]
   * [[techtalk:ih:carb01p|Keihin Butterfly Carb Identificaton]]
+  * [[techtalk:miscres:miscres05#tsb_650-699|See TSB #694 for introduction information on the Keihin butterfly carb]]. \\ Click the link to view the TSB page in the Sportsterpedia. Then click on the "Y" next to #694 to view / download the PDF. \\
+\\
 For Late 1976-1987 Sportsters. \\
 If you are opening up your carb for the first time, you need three things: \\
-  - A FSM (Factory Service Manual) for you year model.
+  - A FSM (Factory Service Manual) for your year model.
   - A factory Parts Catalog.
   - A good rebuild kit (new rubbers all through a carb make a big difference to it's performance)
-The L76-78 Keihin butterfly carbs worked the best and had more adjustment to them. ((oldnavy of the XLFORUM http://xlforum.net/forums/showthread.php?t=877868&page=2)) \\
+The L76-78 Keihin butterfly carbs worked the best and had more adjustment to them. ((oldnavy of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/101363-keihin-butterfly-accelerator-adjustments/page2?t=877868&page=2)) \\
 They had no choke cam, a deeper frost plug in the top and a wider range in them. \\
 Another factory fix was to seal the frost plug in the top with silicone to be sure they weren't leaking. \\
@@ Line 23: / Line 25: @@
 See which best fits the most narrow part (throat) of the venturi. \\
-{{: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 https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/194516-choices-choices-what-carb-for-69-xlch?highlight=keihin#post4226385))
 ====== Choke ======
 On L76-78 Keihin carbs, the choke system is standalone with a choke plate and an actuating rod. \\
 On 79-up carbs, the choke system is composed of a choke, actuating rod and a fast idle cam. \\
@@ Line 38: / Line 38: @@
   - Fully open (off for normal operating temp).
 **79-87 models**: \\
-The choke has 4 basic positions ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1383309&page=2)) \\
+The choke has 4 basic positions ((IronMick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/130833-keihin-fast-idle-pilot-screw-adjust/page2?t=1383309&page=2)) \\
   - Full choke for cold startup (knob all the way in).
   - Choke out a little (maybe 1/2"). \\ (choke plate is still fully open but the fast idle cam moves the throttle valve to the fast idle position)
@@ Line 44: / Line 44: @@
   - Choke all the way out, plate is fully closed and valve is in the highest idle position
-Check your butterfly shaft also. If its loose, the bushings are worn and you'll be sucking air. ((egarrett of the XLFORUM http://xlforum.net/forums/showthread.php?t=575622&page=2)) \\
+Check your butterfly shaft also. If its loose, the bushings are worn and you'll be sucking air. ((egarrett of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/79254-missing-carb-parts/page2?t=575622&page=2)) \\
 ====== Low Speed System (idle circuit) ======
@@ Line 63: / Line 63: @@
   - Adjust idle SPEED screw again to get desired idle speed.
-**Observations from Hopper of the XLFORUM**: ((http://xlforum.net/forums/showthread.php?t=276157&page=2)) \\
+**Observations from Hopper of the XLFORUM**: ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/55576-how-to-tune-keihin-carbs-links/page2?t=276157&page=2)) \\
 <blockquote>I have found that the spring on the idle speed screw tends to creep the idle speed back up if you try to adjust the idle just that little bit slower. \\
@@ Line 80: / Line 80: @@
 **Further explanation from IronMick of the XLFORUM**; \\
-<blockquote>If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=71361)) \\
+<blockquote>If the carb is old and dirty the pilot screw passage may be gummed up such that you will not be able to "gently seat" the pilot screw reliably. ((IronMick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/36692-setting-the-pilot-screw-on-your-ironhead?t=71361)) \\
 If this is the case remove the carb from the bike and clean it up. Some guys try to do carb work with the carb in the bike. This is generally a very bad idea. \\
@@ Line 87: / Line 87: @@
 The screw usually comes out easily. The other parts may require some work. \\
 The best technique is to stick a pipe cleaner in the hole, twist it around, and, like magic, out come the other parts on the end of the pipe cleaner. \\
-    * The pilot screw adjustment mainly affects the idle speed operation of the engine. ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=71361)) \\ This is when the engine is actually idling, and when you release the throttle while riding. \\ If the pilot screw is too lean you get backfire in the exhaust when you throttle down, and white looking spark plugs. \\ If it is too rich you get black sooty exhaust and black sooty spark plugs. \\ Either situation has serious consequences for engine longevity if left unresolved.
+    * The pilot screw adjustment mainly affects the idle speed operation of the engine. ((IronMick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/36692-setting-the-pilot-screw-on-your-ironhead?t=71361)) \\ This is when the engine is actually idling, and when you release the throttle while riding. \\ If the pilot screw is too lean you get backfire in the exhaust when you throttle down, and white looking spark plugs. \\ If it is too rich you get black sooty exhaust and black sooty spark plugs. \\ Either situation has serious consequences for engine longevity if left unresolved.
 The mixture screw does not have a large range of adjustment, if you're running lean, you may need to increase the low speed jet size. \\ (after you have eliminated all other contributing factors) \\
 **Note**: 1966 to 1978 Sportster carbs do not have the O-ring and washer in the pilot screw passage.
@@ Line 104: / Line 104: @@
 </blockquote>
 ===== Air/Fuel Mixture Adjustment =====
 **Low speed / idle mixture screw**: \\
-Other names include the idle mixture screw or the pilot screw. ((IronMick of the XLFORUM http://xlforum.net/forums/showthread.php?t=1383309&page=3)) \\
+Other names include the idle mixture screw or the pilot screw. ((IronMick of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/130833-keihin-fast-idle-pilot-screw-adjust/page3?t=1383309&page=3)) \\
-You may get smoother running by adjusting this screw as it adjusts the flow of gasoline at idle. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=1383309&page=3)) \\
+You may get smoother running by adjusting this screw as it adjusts the flow of gasoline at idle. ((Hopper of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/130833-keihin-fast-idle-pilot-screw-adjust/page3?t=1383309&page=3)) \\
 The idle mixture screw is held in place by a spring on top of the carburetor near the intake mounting flange on all models. \\
@@ Line 183: / Line 181: @@
 With the plug installed, the pilot jet draws fuel from and through the main jet. \\
 You must run with the plug in place or the main jet will be bypassed by the drilled passage and it will run very rich. \\
+**Correction of Lean Mixture Problems Due to the Rubber Bung** \\
 Sometimes, the black plug in the low speed jet is too long and should be trimmed off to allow more fuel in the low speed side. ((oldnavy of the XLFORUM http://xlforum.net/forums/showthread.php?t=877868&page=2)) \\
-Trim off as much as needed to still hold it in without falling out about 1/8". This was a factory fix. \\
+Trim off as much as needed to still hold it in without falling out. Per TSB #707, correct by either modifying or replacing the plug. ((HD TSB #M707 dated December 1, 1976)) \\
+Either cut a plug so it is 5mm (.20") from shoulder to tip or replace it with a new plug (27385-76). Refer to bulletin 694 for disassembly and assembly procedure to remove and replace plug. \\
 Screaming Eagle Keihin carbs do not use the rubber bung. \\
@@ Line 238: / Line 239: @@
 But if you were desperate you could poke a bristle from a wire brush in there, very carefully. \\
 And don't lose the bristle down the manifold, it will wreck your engine, being hardened spring steel. \\
+**Correction of Air Leakage at Carburetor Body Plugs** \\
+As a precautionary measure to eliminate possible air leakage, apply an adhesive type sealer, such as Harley-Davidson Seal-All, to the two welch plugs in top of carb. ((HD TSB #M-707 dated December 1, 1976)) \\
+Apply a minimal amount only to the joints between the edges of the plugs and the casting. \\
 |Idle transfer ports inside. ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=276157&page=3))|Idle transfer ports outside. ((photo by Civil War Harley of the XLFORUM, annotated by Hippysmack  http://xlforum.net/forums/showthread.php?t=2002662&highlight=keihin+accelerator+pump&page=2))|
@@ Line 314: / Line 319: @@
 The accelerator pump is operated by a rod attached to a spring loaded bell crank mounted on the throttle butterfly shaft. \\
 When you open the throttle, the spring is wound up and forces the rod down. How far the rod travels determines how much gas is forced into the carb's throat. \\
+**Correction of Faulty Accelerator Pump Operation** \\
+With engine warm and running at idle, remove air cleaner cover and see if any fuel is leaking from accelerator pump nozzle due to the accelerator pump rod being too long. ((HD TSB #M707 dated December 1, 1976)) \\
+Correct by removing the rod as detailed in bulletin 694 and shortening to 59.50mm. (2.34"). \\
+Caution: Do not over-shorten because this will affect pump action and cause poor acceleration. \\
 ====== Tuning the Accel pump ======
@@ Line 539: / Line 549: @@
 ====== Heat Spacer ======
-**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 that, it is suggested to install a 'new available' spacer block (5895) on 1200CC engines between the intake manifold and the carburetor. \\
-It's purpose was to prevent erratic idle or spit-back through the carb in slow moving traffic or at high ambient temperature. \\
-Some Sportster owners say they have never needed them and others use them regularly. \\
-**Argument for using the spacer**: \\
-((photo by Robicycle of the XLFORUM http://xlforum.net/forums/showthread.php?t=1663198&highlight=keihin+bowl)) ((photo by Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=276157&page=3)) {{ :techtalk:ih:carb:keihin_butterfly_carb_6_by_hopper.jpg?direct&300|}} \\ {{ :techtalk:ih:carb:keihin_butterfly_carb_4_by_robicycle.jpg?direct&300|}} \\
-The Phenolic fiber spacer helps with hot idle or starting problems. One infuriatingly simple thing that affects idle, starting and carb farts when your engine is hot, is this phenolic fiber spacer. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?t=276157&page=3)) It's between the carb and manifold, which some models had and others did not. It stops engine heat from flowing into the carb. If your model doesn't have one of these stock, you can cut one out of a sheet of fiber about 3/16" thick. JP Cycles or others sell one that is a bit thicker and might work even better. There should be a gasket on each side of the spacer while still using the rubber O-ring on the carb flange. Of course, make sure both the carb flange and the manifold are filed nice and flat with a 10-inch flat file first. Without it, your carb can get too hot to touch within minutes of the bike being parked with a hot engine. Even the air filter gets hot. There is a lot of heat flowing from the heads, up the manifold and into the carb which makes it hard to start and idle rough. The heat vaporizes the fuel in the float bowl and it can boil and come out the overflow tube at the bottom of the float bowl. This also means the tiny amount of fuel trying to go through the idle adjuster screw and into the carb throat can also vaporize. Fuel going into the engine needs to be tiny globules of liquid fuel, not vapor. Putting a heat-blocking spacer on is really worth the effort if you ride a lot in city traffic. (where idling at the lights will allow heat to flow into the carb while there is no cooling wind) With a kick only XLCH, the easier hot starting is a Godsend. \\
-Gas getting to the boiling can happen for several reasons. \\
-Having the gas line resting against the engine, the float set too low and others will also attribute to boiling gas. \\
+[[techtalk:ih:carb01#heat_spacer_insulator_block|Click here to see Heat Spacer / Insulator Block]] on the main IH carb page. \\
 ====== Vacuum Ports (83-up) ======
 **VOES port**. \\
@@ Line 638: / Line 636: @@
     * If the problem is crud, then it can often be fixed at least temporarily by partially emptying the float bowl. ((Ironmick of the XLFORUM http://xlforum.net/forums/showthread.php?t=507935&page=2)) \\ While running, shut off the fuel valve, run the bike until it begins to sputter, then turning on the fuel. \\ The sudden rush of fuel may dislodge the crud and you are good to go for a while. This can be done either while riding or while just idling. \\ This should wash out debris in the float valve / seat.
   * **Damage or debris around valve seat**.
-  * **Too high float level**.
+  * **Too high float level**. \\ See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
-    * See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
   * **Worn float mounting tabs, float pin or loose float retaining screw**.
   * **Cracked or damaged overflow tube in the float bowl**.
@@ Line 650: / Line 647: @@
 **Check for**: \\
-  * **Improper idle mixture adjustment**: See [[techtalk:ih:carb01r#overall_adjusting_procedure|Overall Adjusting Procedure]] above.
+  * **Float setting too low**. See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
+  * **Improper idle mixture adjustment**: \\ See [[techtalk:ih:carb01r#overall_adjusting_procedure|Overall Adjusting Procedure]] above.
   * **Damaged mixture screw**.
   * **Clogged bypass or idle ports**.
   * **Clogged slow jet**.
   * **Loose slow jet**.
-  * **Air leaks**.
+  * **Air leaks**. See [[techtalk:ih:carb01r#running_lean|"Testing for air leaks"]] below.
   * **Excess or sloppy fuel from accelerator pump**.
   * **Improper fast idle adjustment on 79-up carbs**:
@@ Line 661: / Line 659: @@
     * A fast idle can also be caused by an advance mechanism that is not functioning correctly. \\
   * **Mechanical issues with choke or throttle shaft / parts**.
+  * **Erratic Idle Due to Fuel Vaporization** (especially in stop and go or at stoplights)
+    * Insure the fuel hose isn't touching a head / cylinder to add extra heat to the fuel.
+    * Consider installing a heat spacer between the carb and manifold. \\ See [[techtalk:ih:carb01#heat_spacer_insulator_block|Heat Spacer / Insulator Block]]
@@ Line 669: / Line 670: @@
   * **Clogged bypass (idle transfer) ports**.
   * **Clogged or too small of a slow jet / bleed tube**.
-  * **Float setting too low**.
+  * **Float setting too low**. See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
-    * See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
 ===== Hard Starting =====
 **Check for**: \\
-  * **Improper idle mixture adjustment**: See [[techtalk:ih:carb01r#overall_adjusting_procedure|Overall Adjusting Procedure]] above.
+  * **Improper idle mixture adjustment**: \\ See [[techtalk:ih:carb01r#overall_adjusting_procedure|Overall Adjusting Procedure]] above.
   * **Choke not adjusted properly / not operating properly**.
   * **Clogged jets or internal passages in the carb.**.
-  * **Wrong float setting**.
+  * **Wrong float setting**. \\ See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
-    * See [[techtalk:ih:carb01r#float_level_adjustment|Float level adjustment]] above.
   * **Fuel valve on tank not turned on**.
   * **Loose bowl screws**.
@@ Line 708: / Line 707: @@
     * Running hot can be caused by vacuum leaks or bad ignition events.
   * **Causes**:
+    * On 1977-up carbs, the rubber plug over the slow jet may be too long causing a lean mixture.
+      * See [[techtalk:ih:carb01r#rubber_bung|Correction of Lean Mixture Problems Due to the Rubber Bung]] above.
     * Jets too small.
     * Float level too low.

Trace:

Differences

Navigation

Search

Toolbox