98 yz80 at high rpm's acts like someone is hittin the killswich

[mphnlh08]

i have this 98 yz80 it was running great one day and the next it started act up. from midrange to topend it acts like someone is hittin the killswich then it will pick back up and then it just keeps doing the same thing i have had it rejeted new top and bottom end what could it be i need help on this so if someone can please help me. thanks

how would i go about checkin the ignition.

i was told there wasnt a powervalve in the 80s. any more ideas.

 

[dirt bike dave]

The power valve might not be opening properly.

Check that first. Something might have loosened up, or it was not re-installed correctly when you had the motor apart.

 

[_JOE_]

It doesn't look like your bike has a power valve. Have you tried a new plug? If so check the main jet for a restriction. If that's ok it may be ignition.

 

[360stunners]

check reeds might be worn ?

 

[mphnlh08]

got new reeds in it anything alse

 

[justalonewolf007]

Were there any differences in temperature on the days you were riding? There is a chance you could be jetted wrong. How long have you had the bike? Is this the first time it's happened?