My piston came apart in my cylinder saturday!! Need advice!!

joelyles2004

Member
Mar 5, 2004
53
0
I'm a newb at the site, and I need some advice, but I think I've got the right idea since I have some 2 stroke repair experience. The side skirt on the intake side of the piston got caught in one of the port windows (openings), and broke a quarter size chunk of it off. Some of it went into the bottom end, and some to the top of the piston. When I got home, I disassembled the bike: Plastics, seat, gas tank, head, hoses, etc, and saw the shavings on top of the piston. I sucked them out with a shop vac, and gently removed the cylinder. While doing that I slipped a rag underneath the cylinder when it was barely loose to catch any debris from further falling in the crankcase. I tried to turn the crank, and it would wiggle a little. Slowly bringing up the debris stuck to it, thanks to the oil left on it. I repeated the process until i got all I could out. Then came the time for the small pieces. I put a paper towel soaked in oil between the crank weights. Amazing! It scooped up the shavings! So every 1 turn, I replaced the paper towel with a new one and they kept coming out. When no more came out, I shined a light inside(between the weights) and saw some micro pieces. I Then took some long surgical tweezers and got the rest out. Next I blew it out with high pressure air & checked it again, nothing. I poured a little 2 stroke oil in the crank area, and spun the crank. No noise at all. It spun flawlessly. The rod is a Pro-x rod and has no play! What luck. I measured the cylinder bore with a digital mic. It was 66.4 mm. That's right at stock bore size. A magnet stuck to the sleeve, so it's steel. I'm just bore it to the next oversize, or whatever it takes to clean it up and put a wiseco piston kit with new gaskets. I also will have some one put a good trail port on it (the best I Know, which will cost $200), and I will be set. I believe the piston got hung up because I've only had the bike 6 months and really didnt realize until now how underpowered my 97' rm250 really was. I rode an 04 stock over the weekend. Wow, I didnt know what i was missing. If you guys have any ideas just post them, anything would help with the extra preparation. I've already read sticky's cylinder cleaning instructions. Thanks. If youre still awake then congrats!

Thanks,
Joe Lyles
 

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