A bit different than the big twin method below..
*Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community
Jetting should be in the area of #46 low jet and see below for recommendations for the high speed jet. Using 2 - #4 washers under the needle for the main jet should resolve any popping back known to be a common problem in the sportsters.
Best to leave the diaphragm alone in the top of the carb. The slide diaphragm can be tricky to reinstall without pinching the rubber.
The vacuum hole is a particular size in the slide and it is for a reason. It governs the movement of the slide for proper fuel delivery. If it is enlarged to 1/8" as some do, the slide action is too fast when the throttle is opened suddenly and it will overcompensate and give you some uneven fuel delivery which will cause surging.
The diaphragm spring establishes a constant tension on the diaphragm and should not be shortened or replaced. Even if you increase the jet sizes to compensate , you still end up with a surging problem.
Shimming the needle up or replacing it should be done with caution and will bring in the fuel curve a bit earlier for better performance.
Removing the idle screw concealment plug will result in a better idle and a bit more throttle response. Care must be taken when drilling the plug for removal not to go through the plug and hit the idle set screw which will turn it inwards and quite often damage the tip.
This pic shows a removal of the concealment plug over the idle mixture screw..
The slow jet is screwed into the carburetor body in the bottom of a hollow well . This jet controls the fuel flow as much as 1/4-throttle.
The proper low jet is usually found to be in the range of #45 or #46 for best results.
Screw in the replacement main jet as follows:
SE air cleaner OR SE mufflers BOTH
883 #165 #170
1200 #175 #180
1200 Sport/International #195 #200
Tighten firmly, but do not strip.
The emulsion tube (A) is threaded into the bottom of the carburetor body. The main jet (B) is screwed into the end of the emulsion tube.
Setting of the idle mixture screw after rejetting the carb will usually find it out about 2 1/2 turns open after LIGHTLY seating it if the proper low jet is installed. If it is open more than this, the low jet is too small and if it is open less then this, the low jet is too big and they should be replaced with the proper size jets.
*Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community
Jetting should be in the area of #46 low jet and see below for recommendations for the high speed jet. Using 2 - #4 washers under the needle for the main jet should resolve any popping back known to be a common problem in the sportsters.
Best to leave the diaphragm alone in the top of the carb. The slide diaphragm can be tricky to reinstall without pinching the rubber.
The vacuum hole is a particular size in the slide and it is for a reason. It governs the movement of the slide for proper fuel delivery. If it is enlarged to 1/8" as some do, the slide action is too fast when the throttle is opened suddenly and it will overcompensate and give you some uneven fuel delivery which will cause surging.
The diaphragm spring establishes a constant tension on the diaphragm and should not be shortened or replaced. Even if you increase the jet sizes to compensate , you still end up with a surging problem.
Shimming the needle up or replacing it should be done with caution and will bring in the fuel curve a bit earlier for better performance.
Removing the idle screw concealment plug will result in a better idle and a bit more throttle response. Care must be taken when drilling the plug for removal not to go through the plug and hit the idle set screw which will turn it inwards and quite often damage the tip.
This pic shows a removal of the concealment plug over the idle mixture screw..
The slow jet is screwed into the carburetor body in the bottom of a hollow well . This jet controls the fuel flow as much as 1/4-throttle.
The proper low jet is usually found to be in the range of #45 or #46 for best results.
Screw in the replacement main jet as follows:
SE air cleaner OR SE mufflers BOTH
883 #165 #170
1200 #175 #180
1200 Sport/International #195 #200
Tighten firmly, but do not strip.
The emulsion tube (A) is threaded into the bottom of the carburetor body. The main jet (B) is screwed into the end of the emulsion tube.
Setting of the idle mixture screw after rejetting the carb will usually find it out about 2 1/2 turns open after LIGHTLY seating it if the proper low jet is installed. If it is open more than this, the low jet is too small and if it is open less then this, the low jet is too big and they should be replaced with the proper size jets.
