I have a 02 f4i that used to ride excellent, now it seems to give alot of low rpm problems when going for slower trix like circle wheelies. I've tried changing spark plugs, timing chain, fuel pressure regulator, air filter & muffler but the problem remains the same. HELP ME PLEASE!!!

 

Check all your vacuum hoses, maybe one is off.
If not that than maybe the Fuel Pressure Reg?

 

I've changed the fuel pressure reg already & no difference I also ran through all my vac hoses & there are no leaks or unpluged hoses

 

Shitty gas, or water in the tank? Sorry, cant think of much else at this hour
Prop the tank up and spraysome starting fluid or something around the airbox and hoses. If it changes the way it idles there might be a leak (maybe you checked well enough the first time but sometimes stuff doesnt line up as planned)

 

OK I'll try that. thanx

 

Word, but dont get blown up, thats stuff is super flammable

 

Alright man I'll try not to. hope it works tho

 

Still got the intake boots?

 

A 636 will fix that problem permanently. Trust me from experiance

 

you have it geared? You have the idle turned up enough? It might not be the motor. Mioght be the bike setup.

 

Wish I could get one but I'm on an Island & the parts for the 636 aren't here, f4i's are popular & parts are easy to get.

 

I run 54 on back & 14 on front, I always keep my idle up 3000- 4000rpm as I said, it used to run good until about 3 months ago.

 

no intake boots plus I've closed off the left side.

 

you flip it hard or anything?

 

I tore it down and fitting it back from scratch, checking & double checking for faulty hoses & injecters getting some fresh paint as well, it's alot of wofk but I hope it pays off in the end.

 

I tore it down a couple a days ago trying to find the problem, looking for broken hoses or vacuum leakage, it's alot of work but I hope it pays off in the end.

 

Timing chain??? Are you sure? Thats in the motor.
Fuel pressure regulator-this is the device on the fuel rail. You changed that? Did you diagnose it first??
If all your vac hoses are correct then next thing to fix would be your fuel filter. Mine bogged like crazy till I changed the fuel pressure regulator and fuel filter.
Your throttle bodies are on flush and tight?
other then that Id say find yourself a manual and start reading.
Goodluck.

 

Problem finally solved I changed the fuel pump plus changed to a different exhaust that gives more back pressure & now it feels great.