I just purchased a used raptor that has a carbon fiber pipe, K & N filter, stock header...It has a spot in the throttle response that has a hesitation to it....The pipe is from Yamaha....does anyone have this pipe and if so what jets should I run?
The guy I bot this from thinks he put a 147 1/2 and 150 in it.

 

First off put the carbon pipe on e-bay and get rid of it. Next i would suggest buying a Team alba stage 2 exhaust. It comes with a complete jet kit and needles and makes a huge difference. I mean this pipe makes a ton of power and its cheaper then all the others. 400.00 compared to the 500.00 plus other pipes on the market. The jets should only be 5 apart. Stock is a 140 and a 145. I run a 160 and a 165 main plus the needles and the other jet that came with the kit. I don't know what they are called. Maybe the pilot jet?? Anyway mine runs perfect except when i'm in a wrong gear going up a big hill. It hits the rev limiter very quickly now. 8hp on the low end 4 on the top end. Wheelies in every gear

 

LOL. I agree that the Alba pipe makes a great difference. It will not wheelie in every gear. 1-3 yes. Yes, the other jets are called pilot jets. If its so great, why are you selling it?

Reddog,

Whats your elevation? Without that nobody can give you an idea of what jets to run. They will also need to know if its running Mikuni (stock style) jets or if the guy installed a Dyno jet kit.

 

The jets he put in were factory type...from mikuni....
elevation is 463 feet
I did move the needle up a notch "as a guy told me too" and it did help...
It will now run without the choke on and the hesitaion has gone away also.
Seems to be running much better....just would like to make sure I have it done right! Without something to compare to hard to tell if it is running the best that it can.

 

If you have the lid on the 147.5 and 150 should be fine. What clip position did you move it to to seemingly correct your problem. If you remove the lid you will need to go to 155/160 at least to get it to run right.

 

Moved the clip on the needle to the last space up...