my buddy has the full system GYT-R on his... thats it. at sea level what are you all running for jets... we cant quite get his right... thanks for the input.

 

I would try a 45 pilot and a 165 or 168 main and about 2 turns out on the mixture screw. Have him get a YZ 450F needle with the clip on the 4th groove.

 

Here's the part # for the needle Yamaha # 5TA-14916-V1

 

he has a gyt-r jet kit... but the dealer wrote down a bunch of different stuff on it and now we cant get it right...

 

Hey, I too am/was having jetting problems with my yfz450 I got a full exhaust, k&n w/ prodesign adaptor and a yz450f exhaust cam. I bought the dynojet jet kit, as it had more of a full range of jets, where as the gytr didnt have much of a range at all. Thus far, I have yet to get the thing totally dialed in. the bottem and mid range are awesome, but about 9,000rpm it stuters, falls on its face, then clears up, just in time to hit the rev limiter at 10,750rpm. Any help in my scenario would be greatly appreciated.

 

................it sounds like in my mind that I am running rich on the main jet, so what I did was back it down a couple of sizes, which as a result made my lowend run extremely lean (spark plug went white) and the topend was still doing what it was doing before (fallling on it's face, and stutering) .............weird. Dont know what to do. I have messed with the needle as well, bringing it up and down a notch. DIDNT HELP. ????

 

Are you running it with the lid on or off of the air box?

 

we tried both...

 

135boom, where do you have your needle set. With mine I am running a GYT-R needle on 4th clip, 170-172 main, 45 pilot and 1.5 turns out on mixture screw. Try that if you allready have not.

 

boom, if it's cutting out on top, go richer on your main jet. Sounds like the low is fine with your needle and pilot adjustments, but the main controls 1/2 and up on throttle...go a little richer, sounds like it's lacking fuel on top revs! Bart, I won't IM you on this one, but there is no way I'm fast enough until I can beat Nate, next year will tell the story!! I finally got my suspension tuned in and it's a whole new machine now, I'm not even gonna worry about aftermarket shocks for a while...these will do!