how to fix a carby flatspot? 1600cc dp, standard vacuum dissy and 34pict carby. the accelerator pump is working and i have tried adjusting the stroke. mainjet is 130 and it has a non standard exhaust.

aftermarket exhaust depending what kind it is they usually come with the preheaters not drilled out
causing the manifold to ice which can give these symptoms or if they are drilled out cos they are feeding from both ends unlike a standard exhaust they dont work properly and carbon up
other than that a blocked or to smaller idle jet

hth
Joel

preheat is working o.k. its a gt 2 tip exhaust.

Try a 135 main jet.

thanks , dave.

make sure the little squirter thing in the top is pointed to the opening side of the butterfly