85 250r troubles

[bingham]

Lately I have been riding my bike in the same temperature every other weekend and it feels as it is throwing the jetting off. The throttle past half seems to give no increase in speed. Gears run through well and when bike tends to run hot it runs like junk. After i get the crab rejetted it runs well for a day of riding then after that its back to crap. Any suggestions? thanks

[Dirtcrasher]

Plugged gas cap vent? Poor fuel delivery - tank filter,line or float??

Whats Mr. sparkplug sayin???

[bingham]

Pulled the plug and it was easly noticed rich. But why should i need to rejet it so often when no changes in riding areas or anything?