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[greeny250sx]

allright..promblem..

250sx..
2000
full procircit..
boyseen reeds..
and can not get the jetting right..

5th gear topped it just dies..
and sometimes in 4th to..
i went richer and leaner..and can not find the right solution..
anyhelp?

[fletchman919]

You need to take a plug reading in third gear pinned. Kill the engine and keep the throttle wide open. After it dies, let off the throttle and pull the plug. If it's whitish, get a bigger main. If it's black, get a smaller main...

Your description was very to the point. Are you positive jetting is the problem?

[greeny250sx]

i reallly dont know..when i take my carb off..theres an electrical plug to it?
i have no idea what this does..
my friend said blasters have the same thing?
so when it gets stuck wide open it limits the amount of gas alloweded into the carb..

know of anything like that?

[MX86]

throttle positioning sensor.. adjusts the timing to the position of the carb.. most newer bikes have it.. supposed to improve thottle responce..

[greeny250sx]

would that affect the boggin out in the later gears?
i know my way around an engine..but i seriously have NO idea whats wrong with it..i tried pratically everything

[MX86]

i would say you have a air leak on one of the crank seals...

i doubt it is the jeting

[greeny250sx]

what do i do to fix that

[MX86]

unfortunatly if that is the case you would have to split the cases and replace the seal...

[holtzer1]

it is NOT a throttle position sensor. its a stuck throttle shutoff circuit. if it runs...thats not the problem. theres a switch on the carb and one on the throttle...they work in sync or it shuts off spark...does absolutelt nothing with fuel.
its not a crank seal...crank seals would cause a lean condition regardless of what gear your in, and would have been compensated for with the fatter jetting.
i'm gonna say its definitely a jetting issue...youll just have to do a plug check with a brand new plug to know which way to go.

[fletchman919]

Originally Posted by holtzer1

it is NOT a throttle position sensor. its a stuck throttle shutoff circuit. if it runs...thats not the problem. theres a switch on the carb and one on the throttle...they work in sync or it shuts off spark...does absolutelt nothing with fuel.
its not a crank seal...crank seals would cause a lean condition regardless of what gear your in, and would have been compensated for with the fatter jetting.
i'm gonna say its definitely a jetting issue...youll just have to do a plug check with a brand new plug to know which way to go.

Holtzer hit the nail on the head. A crank seal leak would cause a constant lean condition and the TORS will kill the spark...

You should really take a plug reading first. We're kinda shooting in the dark without knowing how your jetting is.