my son has an 87 250x and recently started smoking very badly. assuming he had broke a ring or scored a cylinder i tore it down to find nothing obviously wrong. if you know of anything that could cause sudden and severe oil burning beside ring cylinder or piston wear i would like to hear your ideas. anyway i'am going to have the cylinder bored and refresh the topend. what is the best bang for your buck. going to a larger bore? high compression piston. will i have to rejet if i do either one? a pipe seems to be the best bang for your buck but which one have you guys found to be the best? we ride a lot of trails and a little track stuff but seldom do we wind it all the way out. appreciate any ideas
thanks
dan

 

Did it smoke all the time or just when you started it up? If it smoked all the time then your rings were bad. If it just somked when you started it up and quit once it warmed up then your valve seals are bad. Now valve seals will run you about $10 plus whatever labor is. I wouldn't go any higher then 11:1 compression or else you can't run pump gas. With 11:1 you need to run 92 or 93 octane. You might not have to rejet. You just never know untill you try it. The best pipe in my humble opinion is the powroll 3" supertrapp. www.powroll.com It comes with an oversize header and a spark arrestor all for $200. I have it and I love it. It gives you great low end and you can add or subtract disks in the silencer to tune where you want the most power.

 

thanks i will look into that pipe. it smoke a little all the time but we were out riding last weekend and the motor almost disappeared from all the smoke it was blowing.