FULL throttle missing

What should I change with my jetting when the motor breaks down,miss's at almost full throttle.

I'm useing standard air jets maj200 & paj75.

mj155 & pj42.

needle DRM#4.

bottem & mid range is fabuous. Wheel stands every where.

The bike is wr timed with lid off.

From what I've read it sounds like it is too rich, but I'm only running a #155mj with a #200maj which sounds lean compared to what other people are useing.

I've tryed coming up one clip, needle down one but it never improved any. Only dropped mid range performance.

I've tryed bigger mains but that decreased mid range performance aswell & never improved the problem.


Skippy Try 165 mj and third clip, sounds like it may be too lean.

Er...if you are full throttle and it misses and coughs with fabulous performance everywhere else, you are probably hitting the rev limiter.

I had the same problem when I switched to YZ timing, changed my jetting & pipe. You need to shift earlier of this is the case. Also..

what gearing are you running ? This could also be the problem. I was running 13-53 before the changes to jetting and had to change to 14-53. The bike just revved that much quicker than it had before.

Hey Missile,

I'm thinking you might be right.

I'm running 14/52 gearing but I thought maybe there were still more revs left.

But if you think about it I would only use that part of the throttle on the road. You could never use that part of the throttle in the bush.& not break bones.

Does anybody know at what revs the rev limiter cuts in, & a way of doing a rev check.

i go with the blue beast. maybe a 160/162 and then needle down one clip.

the taller gearing will show up your jetting problems more clearly.


not sure how this is gonna work on a four stroke but it works great on a two. Try riding it with the choke on. If it still misses its the rev limiter. If it clears up or gets better the jetting is too lean.

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