ok i have a 03 f4i......its a stunt bike...i have kleen air mod,tip sensor mod,idle mod done to the bike......ok so the bike starts up runs great.....but it stubmbles on its self till about 2,500 rpm then is great....this is where it gets interesting.....i have a stock pipe cut down and a aftermarket M4 pipe.....i take the pipe off and it runs purrrfect no hesitation only when running any pipe on there it does it???????WTH...checked fuel pump good...swapped press reg good....someone anyone...i have a show coming up and need this resolved

 

My two cents:

I'd say it may have something to do with your jetting/carbs. You're removing the backpressure when you take that pipe off.

 

yea i was thinkin the same thing but......it does the same thing with either pipe.....its like it has to much back pressure....so thats when i swaped it out with the m4 pipe i have but same result............

 

ummm F4i doesn't have cabrs or jets get a pcIIi and get it dyno tuned

 

yea i could get a pcIII......but that wouldnt be an answer just away around the problem....

 

^ What???

That would solve the problem. You could also reverse all the mods and that would solve the problem.

It has to do with back pressure and fuel mapping. PCIII will change that.

 

yes i know that...but ,dont understand why theres to much back pressure????im simply tryin to find the problem not just a quick fix......haha already tried that put everything back to stock....still same thing

 

Only code I'm getting is 14 which is injector 3 the starter rolls and the fuel pump primes and when clicking the start button the injectors all fire even though it's throwing that code 14