well i rebuilt the top end of my bike. its a 95 CR250. couldnt get it started the other day. then today we finally fucked with it enough and got it started. but once it started it just spewed oil. like so bad that my buddy was behind me and got it all over his face. on his shirt and it was dripping off of my rear fender. now i called a few places and they assume it is the crank seal i woul dhave to split the case and replace it. the only thing is that i never touched that what so ever. i just pulled the head and cylinder wall off.
here is the question. would this problem be caused by a bad lower piston ring? would this let oil up into the exhaust? my plug was not fouled at all but there was oil everwhere. thanks for the info
yea sounds like a ring issue. its letting oil get in the chamber and not allowing it to fire and stay running then puking out oil out of the motor. tear it down and reset teh ring if possible
thats what everyone is saying. but i never touched it. just between two days it does that? i could imagin if it was slowly getting worse and worse. but it happend as i fucked up one of the rings and did the top end. well i got a new ring we will check this first.
The way it was explained to me was the crankcase is under pressure in a two stroke…the crank seal is a pressure seal (ie holds compression)…fresh rebuild, good ring seal = more stress to the seal.
well i got the new ring in now i just need to get it started. it isnt blowing white smoke when im trying to start it as of now. hopefully get it started this evening and get all the oil out of the exhaust. i think that it was just the ring. we will see though.
these don’t have oil rings, he rebuilt it with new rings, then that’s not the problem. the rings will only fit one way because of the pin sticking out.
talk to don about this…but isnt there letters that represent casting runs of the cylinders and stuff for each yr / models? like u cant just say i need a 95cr250 piston. i thought there was a letter on the cylinder that u had to match the piston with… i dunno maybe that was just on yamahas but i know mine always had that. also, did u not put new rings / gaskets in w/ the new piston? that would probly be bad. what condition is the cylinder in…did the bike blow up or just need freshened up??