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techtalk:ih:carb01 [2019/10/08 02:06] hippysmack [Other HD Keihin Carburetors by Year Model] |
techtalk:ih:carb01 [2019/10/08 02:14] hippysmack [Sub Documents] |
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| * **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)) | ||
| - | * **Additional Tips** on usage: | + | |
| - | * Make sure the low speed and main jets are larger than stock to match the more free-flowing aftermarket exhausts and air filters we all seem to run. ((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?threadid=659533)) | + | |
| - | * Do not run a worn out ignition auto advance unit. It makes carb farts that you would swear were lean low speed mixture.((Hopper of the XLFORUM http://xlforum.net/forums/showthread.php?threadid=659533)) | + | |
| * Integral Float Chamber | * Integral Float Chamber | ||
| * Manual Choke | * Manual Choke | ||
| * 3 different models | * 3 different models | ||
| * Model Year Changes | * Model Year Changes | ||
| - | * **Tuning** | ||
| - | * The usual method to set idle mixture/speed is: | ||
| - | * First: Set idle MIXTURE screw to 7/8 turns out. Get the bike hot. Set idle at comfortable speed with the idle SPEED screw. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
| - | * Second: Adjust the idle MIXTURE screw to the point where engine runs the fastest. This is optimum mixture. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
| - | * Third: Adjust idle SPEED screw again to get desired idle speed. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
| - | * 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. So I adjust the idle speed screw right down too slow, then nudge it up slightly faster until I get the speed I want, then it stays there. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
| - | * If your bike idles best with the idle mixture screw less than ½ turn open, you need a smaller low speed fixed jet. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
| - | * If your bike idles best with the idle mixture screw more than 1-1/4 turns open, you need a larger low speed fixed jet. | ||
| - | * This is real important. It also is the way to stop “carb farts” – spitting back or backfiring through the carb. | ||
| - | * If your Ironhead has aftermarket free-flow exhaust and airfilter on it, it will almost certainly need a larger low speed fixed jet, and most likely a bigger main jet too. But it is the low speed jet that affects the dreaded carb farts. Main jet affects mixture at wide open throttle and if left lean can overheat the engine, or burn holes in pistons. ((Hopper http://xlforum.net/forums/showthread.php?t=276157&page=2)) | ||
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| - | |{{techtalk:ih:carb:hoppers_77_keihin_carb_pic_1.jpg?direct&300|}} |{{techtalk:ih:carb:hoppers_77_keihin_carb_pic_2.jpg?direct&300|}} | | ||
| - | |1977 Keihin 38mm non-CV pic 1((Hopper from the XLFORUM http://xlforum.net/forums/showthread.php?t=247853))|1977 Keihin 38mm non-CV pic 2((Hopper from the XLFORUM http://xlforum.net/forums/showthread.php?t=247853))| | ||
| ==== Sportster Keihin Butterfly Carburetors by Year Model ==== | ==== Sportster Keihin Butterfly Carburetors by Year Model ==== | ||
