Re-Jetting CV

[Bill]

Mike, A friend has a 05 Sporster 1200, stock, and he is putting on 3" cycle shack slipons. What would be a good start on re-jetting and or raising needle. With the stock mufflers on it coughs threw the carb. We took out the plug to the idle mixture screw and tried to get the cough out. No matter how far we screwed the screw out , it still had a cough. Could it be a intake manifold leak? Thanks.

[Mike]

You always want to make sure you do not have intake leaks before jetting carbs but it does not happen as often as many think (I.E., a lot of manifolds are checked for leaks with few found).

Having said that, depending on where the bike was intended to be marketed, your stock jetting should be 42 slow and 180 main. As a sttarting point, I would recommend a 45 slow, 190 main, two needle shims (typically available at a Kawasaki dealership) and 2 1/2 turns on the idle mixture screw. If fuel mileage suffers too much, you can try one needle shim. Adjust the idle mix for best idle quality (when warm) from the 2 1/2 turns (typically in, but not more than one full turn).

Know that you may not be able to complelety eleminate the cough due to the lean and lagging accelerator pump and overall emmisions design of the carb. The above changes should make it tolerable.