I have a 99 300ex runs good and lots fun on the trails but it cuts out in high gears when u give it full throttle. The bike is all stock from what I know I got it on a trade so I have no idea if the owner before me has bored it or anything. I noticed when doing a good cleaning that the head has been taken off bc of the rtv glue on it. id rather not take it all apart.
My question is if its been bored over wont the carb need to be jetted higher and if so should I start by jetting it a step up at a time.
It has 122 main, 38 pilot, 3rd groove needle, 2-1\4 turns out
Oh and it will cut out bad if I snap the throttle fast and hard when its idleing

 

check fuel filter ? plug fouled ? air filter clean ? chock adj. correctly? any 1 of these can cause problem. smoking ? running lean or rich ?