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So I come home to my dads yesterday to find a 2003 CRF150F sitting in the basement partially taken apart. At first I think..SWEET. But I then realize this isn't good.
My 16 year old brother's friend went out and bought it for $800. He has very very little knowledge about bikes/motors/maintenance. I guess the bike blew all sorts of black smoke. Inside of exhaust was full of oil/build-up all the way to the valve.
My brothers friend though to himself that it is just piston rings. I'm not so sure.
I eventually get suckered into helping them because that's what big brothers are for, and hey, I like this shit. I pull the motor, got the cylinder head off, then the cylinder (which fought me like you wouldn't believe) and finally the piston. Cylinder walls noticeably had oil on them. Also, the exhaust valve was absolutely filthy. I popped out the exhaust valve (against my better judgement because I know how much of a bitch it is to get it back in without the spring compressor) and the seats were surprisingly decent. They should lap out and be good, no major imperfections.
But now onto the cylinder and piston. There is scoring. It doesn't FEEL bad, but it LOOKs pretty bad. What do you think? Cyclinder and piston are junk?
Here are his options as I see them:
-Replace rings, put back together, hope for the best
-Send out cylinder, buy new piston/rings, have a solid bike
-Buy new cylinder (haven't looked up prices but for a 150 it may be cheaper than sending it out) and new piston/rings, have a solid bike
Remember. This is a 17 year old kid who just spent all his money on the bike itself...a few hundred dollars will kill him. This isn't my brothers bike, otherwise I'd help him buy the parts.