it's not. it's whatever my mechanic orders from yamaha. i would imagine it's mikuni. i would like to learn how to rejet it myself. don't like spending 45 bucks every time. will having it put on a dyno show whether it's rich or lean?

 

Some dynos have O2 sensors that would tell you where your jetting stands. Good luck findig a dyno around here, maybe you are close enough to Memphis to find one. I have had no luck down here. It seems to me that it might be your needle is to high, try lowering it one notch and see if that helps. This means moving the clip up. I am no expert on jetting either but it is all pretty much trial and eror, alot of error in my part. Get a manual to show you the inside of the carb. After you know what is what it is fairly easy to change stuff, getting it right is another story. Your spark plug is the biggest tool when it comes to rejetting.

Does anyone know how to check jetting accuracy in the 1/4-3/4 range?

 

Ok, I am working through some jetting problems also. I talked with Dynojet yesterday and the tech said it was perfectly normal to have a glowing head pipe. Due to the thinner metal used in the aftermarket pipes you will have a red glow from your head pipe. If you don't and you are using an aftermarket pipe then you are probably too rich. I tried the 25's and 27.5's, they do reduce the glowing, but the throttle response is definitely not there like it is with the 22.5's. Just my $.02.