sounds like its under fuelling to me im afraid,when you open a throttle the first thing it does is let more air into the engine not fuel the fuel will only ome up through the jets when the engine revs rise and then there is a vaccum in the venturi of the carb which pulls the fuel up throught the jets.if you have a race pipe on it the jet should be made bigger it needs the extra fuel,if it didnt run badly at first its because the compression was better then than it is now.ill tell you what ........
you take your air filter out and see what happens.i would bet you it runs worse! if it was rich and too much fuel going through it would run better without the filter.anyone who says putting a bigger jet into a carb when you fit a race pipe is the WRONG thing to do is WRONG and obviously has no idea at all of what they are talking about.it needs the right jet for the pipe and that whatever it may be it is a bigger one then the standard one if you have a race pipe.(expansion chamber).i have worked as a motorcycle mechanic for over 16 years and i know what im talking about.but you call matty below if you want and he can tell you what he thinks,he may be older and wiser than me !
adam bike doctor
March 2010
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