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techtalk:ih:carb01 [2022/04/19 02:57]
hippysmack [Sportster Keihin Butterfly Carburetors by Year Model]
techtalk:ih:carb01 [2023/12/04 20:56]
hippysmack [Other HD Keihin Carburetors by Year Model]
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 ===== Mikuni XR-750 racing engines only ===== ===== Mikuni XR-750 racing engines only =====
- 
  
 **1972-1980** **1972-1980**
  
-Through 1980, XR-750 engines were equipped with a 36mm Round Slide((http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=3)) Mikuni. Below is a chart of the standard jetting of these carbs. Final jetting may vary. ((1972-2003 HD XR-750 Service ​Manua pg 39))+Through 1980, XR-750 engines were equipped with a 36mm Round Slide((http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=3)) Mikuni. Below is a chart of the standard jetting of these carbs. Final jetting may vary. ((1972-2003 HD XR-750 Service ​Manual ​pg 39))
  
 +^{{techtalk:​miscres:​instruction_sheet_header_4.png?​nolink&​850|}}|||||||
 |36mm Carb Types|Main|Pilot|Needle|Needle Jet|Slide|Air Correction Jet| |36mm Carb Types|Main|Pilot|Needle|Needle Jet|Slide|Air Correction Jet|
 |VM-36-1 \\ VM-36-4 \\ VM36/​39|240|25|6F5|159-P4|2.0|1.0| ​ |VM-36-1 \\ VM-36-4 \\ VM36/​39|240|25|6F5|159-P4|2.0|1.0| ​
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 Engine upgrades prompted HD to recommend the use of Mikuni'​s 38mm Flat Slide carburetor (not supplied with the engine kit). Recommended jetting chart below.((1972-2003 HD XR-750 Service Manua pg 39)) Engine upgrades prompted HD to recommend the use of Mikuni'​s 38mm Flat Slide carburetor (not supplied with the engine kit). Recommended jetting chart below.((1972-2003 HD XR-750 Service Manua pg 39))
  
-|38mm Carb Types|Main|Pilot|Needle Jet|Slide|+^{{techtalk:​miscres:​instruction_sheet_header_4.png?​nolink&​850|}}|||||| 
 +|38mm Carb Types|Main|Pilot|Needle Jet|Slide||
 |TM38-85 (47mm spigot dia.) \\ TM38-86 (43mm spigot dia.)|210-260|20-25|6FM46|Q0,​Q2,​Q4|4.0| |TM38-85 (47mm spigot dia.) \\ TM38-86 (43mm spigot dia.)|210-260|20-25|6FM46|Q0,​Q2,​Q4|4.0|
  
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 So any of these 3 sizes will work. So any of these 3 sizes will work.
  
 +^{{techtalk:​miscres:​instruction_sheet_header_4.png?​nolink&​850|}}||
 |**Mikuni** (**XR-750 Racing Engines Only**)|| |**Mikuni** (**XR-750 Racing Engines Only**)||
 |VM-36-1 \\ VM-36-4 \\ VM36/​39|1972-1980 XR-750 / 36 mm with a round slide ((http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=3))((1972-2003 HD XR-750 Service Manual pg 39))| |VM-36-1 \\ VM-36-4 \\ VM36/​39|1972-1980 XR-750 / 36 mm with a round slide ((http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=3))((1972-2003 HD XR-750 Service Manual pg 39))|
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 The VM38-"​9"​ was setup and extensively tested by Jerry Branch for the stock Sportster engine using flow bench tech for the time. ((simeli of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1636803&​page=2)) \\ The VM38-"​9"​ was setup and extensively tested by Jerry Branch for the stock Sportster engine using flow bench tech for the time. ((simeli of the XLFORUM http://​xlforum.net/​forums/​showthread.php?​t=1636803&​page=2)) \\
  
 +^{{techtalk:​miscres:​instruction_sheet_header_4.png?​nolink&​850|}}|||||||
 |38mm Carb Types|Main|Pilot|Needle Jet|Throttle Valve|Jet Needle|Air Jet| |38mm Carb Types|Main|Pilot|Needle Jet|Throttle Valve|Jet Needle|Air Jet|
 |VM38-9 (43mm spigot)((IronMick http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=2))|330|30|Q-2|2.5|6DP1|0.5 \\ 2.0| |VM38-9 (43mm spigot)((IronMick http://​xlforum.net/​forums/​showthread.php?​t=2006195&​page=2))|330|30|Q-2|2.5|6DP1|0.5 \\ 2.0|
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     * **Operation**:​ Fuel from the gas tank passes through the fuel valve, onto float chamber. The fuel entering causes the float to rise until it shuts off the fuel valve, stopping the flow at a level predetermined by float level setting. ​ ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))     * **Operation**:​ Fuel from the gas tank passes through the fuel valve, onto float chamber. The fuel entering causes the float to rise until it shuts off the fuel valve, stopping the flow at a level predetermined by float level setting. ​ ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))
     * **Idle or Slow System**: The slow system functions at idle, low and intermediate speeds when throttle valve is closed or only partially open. At idle, fuel enters the main jet and, after being metered there, enters the slow jet where it is metered again. Fuel from the slow jet enters the slow jet bleed tube where it mixes with air through the slow air passage. Fuel mixture is regulated by adjusting the idle (low speed) mixture screw. When the throttle valve is closed, fuel mixture flows into the venture almost entirely through the idle port. As the throttle valve gradually opens, fuel mix discharge is transferred to the bypass. The slow jet bleed tube is actually a part of the slow jet. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))     * **Idle or Slow System**: The slow system functions at idle, low and intermediate speeds when throttle valve is closed or only partially open. At idle, fuel enters the main jet and, after being metered there, enters the slow jet where it is metered again. Fuel from the slow jet enters the slow jet bleed tube where it mixes with air through the slow air passage. Fuel mixture is regulated by adjusting the idle (low speed) mixture screw. When the throttle valve is closed, fuel mixture flows into the venture almost entirely through the idle port. As the throttle valve gradually opens, fuel mix discharge is transferred to the bypass. The slow jet bleed tube is actually a part of the slow jet. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))
-    * **The Main System**: The main system functions at intermediate and high speeds as the throttle valve opens further. Fuel is metered by the main jet and enters the main jet air passage. The fuel/ air mixture then exits from the main nozzle and into the venturi. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))+    * **The Main System**: The main system functions at intermediate and high speeds as the throttle valve opens further. Fuel is metered by the main jet and enters the main jet air passage. The fuel/air mixture then exits from the main nozzle and into the venturi. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM)) There is no metering needle.
     * **The Accelerating Pump System**: The accelerating pump system works with sudden throttle openings (rapid acceleration) to quickly inject fuel into the carb to provide extra fuel for the engine demand. Rapid throttle action pushes the pump rod down, flexing the diaphragm, which compresses fuel underneath the diaphragm, forcing it up past the check valve and out the pump nozzle into the venturi. The check valve prevents backflow while the pump nozzle meters the flow. Spring action then returns the diaphragm back to it's original position. As the diaphragm returns, a new supply of fuel flows in and under it so the system will be ready to repeat the cycle with the next rapid throttle action detected. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))      * **The Accelerating Pump System**: The accelerating pump system works with sudden throttle openings (rapid acceleration) to quickly inject fuel into the carb to provide extra fuel for the engine demand. Rapid throttle action pushes the pump rod down, flexing the diaphragm, which compresses fuel underneath the diaphragm, forcing it up past the check valve and out the pump nozzle into the venturi. The check valve prevents backflow while the pump nozzle meters the flow. Spring action then returns the diaphragm back to it's original position. As the diaphragm returns, a new supply of fuel flows in and under it so the system will be ready to repeat the cycle with the next rapid throttle action detected. ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM)) 
     * **The Choke System**: The choke is manually set by pulling out on the choke button. Pulled all the way out is fully closed (for cold engine), partially open (for warm engine) or pushed all the way in, fully open (for warm engine). ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))     * **The Choke System**: The choke is manually set by pulling out on the choke button. Pulled all the way out is fully closed (for cold engine), partially open (for warm engine) or pushed all the way in, fully open (for warm engine). ((1970-1978 HD XL/​XLH/​XLCH/​XLT 1000 FSM))
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 ==== Other HD Keihin Carburetors by Year Model ==== ==== Other HD Keihin Carburetors by Year Model ====
- +^{{techtalk:​miscres:​instruction_sheet_header_4.png?​nolink&​850|}}|||||||| 
-^Other HD Model^Year \\ Carb Used^Serial Number^Flange / \\ Casting \\ Number Main Jet \\ Size  ​^Low Speed \\ Jet Size^Initial Mixture \\ screw setting^Accel Pump \\ spring position^+|Other HD Model|Year \\ Carb Used|Serial Number|Flange / \\ Casting \\ Number Main Jet \\ Size  ​|Low Speed \\ Jet Size|Initial Mixture \\ screw setting|Accel Pump \\ spring position|
 |All FX|76|27155-76| 860A ((Hd TSB #M-713 dated June 10, 1977)) \\ 860B |185 ((Hd TSB #M713 dated June 10, 1977))|100|7/​8|center| |All FX|76|27155-76| 860A ((Hd TSB #M-713 dated June 10, 1977)) \\ 860B |185 ((Hd TSB #M713 dated June 10, 1977))|100|7/​8|center|
 |All FL|76-E77|:::​|:::​|:::​|:::​|:::​|:::​| |All FL|76-E77|:::​|:::​|:::​|:::​|:::​|:::​|
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 |FXWG|1980|27470-80 ((1971-1984 HD FX Parts Catalog pg 27))|B28D|160|72| |FXWG|1980|27470-80 ((1971-1984 HD FX Parts Catalog pg 27))|B28D|160|72|
 |FXS-80 \\ FXEF-80 \\ FXB|1980|27472-80A ((1971-1984 HD FX Parts Catalog pg 27))|B79D|160| |FXS-80 \\ FXEF-80 \\ FXB|1980|27472-80A ((1971-1984 HD FX Parts Catalog pg 27))|B79D|160|
 +|  |1981 ?​|27494-81|B78E|
 |FLH-80 \\ Classic|1981-1984|27494-81A ((1966-1984 HD FL Parts Catalog pg  (99456-84B) 33))|B78F|165|70| |FLH-80 \\ Classic|1981-1984|27494-81A ((1966-1984 HD FL Parts Catalog pg  (99456-84B) 33))|B78F|165|70|
 |FXEF-80 \\ FXE-80|1981-1983|27472-81A ((1971-1984 HD FX Parts Catalog pg 29))|B79F|160 (FXEF-80) \\ 165 (FXE-80)|72| |FXEF-80 \\ FXE-80|1981-1983|27472-81A ((1971-1984 HD FX Parts Catalog pg 29))|B79F|160 (FXEF-80) \\ 165 (FXE-80)|72|
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 **Here are some part numbers for the different insulator blocks used on 4 stroke Harleys**. \\ **Here are some part numbers for the different insulator blocks used on 4 stroke Harleys**. \\
-There is no known insulator block that was factory installed on a Bendix Carb. \\+There is no known insulator block that was factory installed on a Bendix Carb as used on Sportsters. \\
  
   * 27412-57 for 57-65 XL FL, FX. (Linkert)   * 27412-57 for 57-65 XL FL, FX. (Linkert)