help with honda atc 250r 1986 ?runnig poor at top speed!

[judge]

:wondering hi to anyone who can help.i just got a 1986 honda atc 250r,all stock ,but has esr pipe , silencer. anyhow it starts 1st kick, idels right, everythink works as it should. but when i get to the top end speed. it spuders and dies, then when it gose down in speed it come to life again. the motor was completly rebuilt top to bottom. i cleaned out the carbs , and jets, all fluids where changed,[with honda line oils]i run it with 32to1 honda two stroke oil,should i run it at 20to 1 or is it the cdi box or coil. any help would be useful. i had one brand new back in 1986, and it never did this.twenty years later i got another one thanks to my loveing wife.please help. thanks to all. judge

[Liquid-Darkness]

Drop your main jet size on your carb one outa time till it revs clean.

[badasskfx]

what size main jet are you running? is your lid on or off?

[jeffatc250r]

Try one simple thing first for hahas, try changing your plug. When my r starts to foul one out it still runs great down low, but wont clean out. For me everytime this happens its almost always a $2 fix.

[Rustytinhorn]

Before you do any jetting, take your air filter off and run it up and down the street a few times and see if that makes any difference. You might need to adjust the main jet.