ok so i have a 250 ex. used pretty good a put a big gun rev limiter on it, a dyno jet stage 2 jet kit in it a a yoshimeria full exhaust kit on it witch i took the baffle out of. it ran good for a while.. i tweaked the carb ran good.. then it started smokein and it all went to hell. it will burn all of the oil in less than an hour and smokes like nothin else ive ever seen before. i final came to the conclusion that i put too big of a jet into it and that it was dumping to much Fuel (do to the flame and back fireing on acation). i figure that the exes fuel had hardened the cylinder wall and was causing the oil to blow past the rings. i havent had time to take it apart due to the fact that im in the military and not home much at all. but i dident know weather i had to buy a new cylinder or if i could just get a sleeve. i see they have sleeves for sale on line. but i dont know if the sleeve would press out or if they dont. i am new to this yahoo answers thing so please bear with me! thanks for the input!

All the oil in 1 hour!!!! Wow that’s pretty bad. You would be better off to get an oversize piston kit for your quad. Also while that work is being done do the valve stem seals and check the guides.

You could also try some Cleens (ac delco combustion cleaner). If you spray an ample amount of this in the cylinder and let it sut overnight it may free up some sticking rings and bring your compression back up again.