riddle me this............03 f4i....bike starts up runs good but stumbles on hard acceleration till about 2,500....now this is where it gets good....i have a chopped stock pipe...i take it off the stumble goes away........i have a M4-pipe put it on same thing still stumbles till about 2,500...only way it will clutch up is with out a pipe on it....gotta have a pipe for the spots i ride in dont wanna attract any unwanted attention.....its SF,kleen air mod ,tip sensor mod,idle mods are all done ive changed them back to stock same thing........


someone anyone

 

... Strange, normally it works the other way. Ck for vacuum leaks to the fpr, it can cause a rich condition that will make it fall on its face with any backpressure.