OK my buddy has a 05 636 and ordered a full race exhaust for from yoshi i beleive. well he went ahead and took the old exhaust off then comes to find out it doesnt ship till the 30th or some shit. so he put his stock stuff back on and he says it isnt running right. when he gives it full throttle it is not goin as fast and he says it stops pullin at 9000, but the revs will get higher. any ideas what the problem might be? i think it might be the little butterfly thing in the exhaust stayin closed but i dont really have any idea.

 

It kind of sounds like the clutch is slipping. It could be a coincidence that it happened as he removed the exhaust. But without seeing the bike it's tough to diagnose.

You can check the exhaust valves to see if they are opening and closing by reving the bike in neutral. But if it was the exhaust valve it probably would just fall on it's face and not continue to increase RPM.

 

good ideas. im almost sure it isnt the clutch though just because the bike has only 1100 miles on it. so i doubt it is worn already. i will check the bike in netral though. see if it is pushin alot of exhaust out.thnx

 

Is his FI light coming on?

 

you have an exhaust leak, your loosing back pressure. remove your exhaust and back track everything you did