HELP,07 yz450f 5 gear tap out stuttering ?????

:thumbsup: I have a 2007 yz450f runs real good except in 5 gear tap out I have a very quick stutter or miss fire not sure??? sound like that anyway.Ive tried to go up and down on the jetting just to c if it would help, nope same thing.Ive check valves clearance they check ok,took the carb apart also check ok. Ive been running a DR.R pipe no problem last year.SR this is the best way a can explain this weired thing.I'm new to these 4 strokes so I'm lost right now don't know where to look.

Its most likely that your Main Jet is off a size or 2.

Does this occur only in 5th?

If so, does it occur through out the power range under haevy throttle, or only at very high revs?

it only happens when im in 5th gear, almost tapped, i can ride down a road 5th gear 3/4 throttle and it works fine, but as soon as i go full throttle, it starts acting up, from 1st gear to 5th gear 3/4 throttle the bike runs fine, but that last 1/4 throttle, not so fine haha, maybe something with the CDI??...maybe electrical??..not to sure not to familiar with this stuff

it only happens when im in 5th gear, almost tapped, i can ride down a road 5th gear 3/4 throttle and it works fine, but as soon as i go full throttle, it starts acting up, from 1st gear to 5th gear 3/4 throttle the bike runs fine, but that last 1/4 throttle, not so fine haha, maybe something with the CDI??...maybe electrical??..not to sure not to familiar with this stuff
In your case, if the "miss" seems very pronounced, and mechanically almost violent, as if the chain were skipping teeth, it may be a worn set of gears (locking lugs on the sides) and a bent shift fork causing the gears to force out of engagement, then slam back in again.

If it really seems more like a miss, it could be a faulty plug, or it could be a main jet issue. If it is jetting, and the miss is regular in nature ("dot-dot-dot-dot"), it could be too rich. Check your air filter, and if it's OK, try a smaller main jet. If it's irregular, (like, "dot-da-dot-dadot-dot) (best I can do, sorry), and accompanied by an occasional loud pop out the exhaust, then you might lean, and need a bigger main.

I'm having the same problem and I've switch out everything that you could have switched on the bike, CDi,plug , plug boot , wire harness,stator and even a diff carb.. no luck...even put my carb on a diff bike and the other bike ran great.Also checked the timing and all is ok....called a tech from a race team and he said to do a leakdown test ? ok going to do this ....what do you guys think?any other ideas?

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