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piston fell apart


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What would cause a piston in a 2-stroke quad to fall apart? This happened to my blaster a little while back and I dont know why I havent asked this earlier...

I was riding it rather lightly, just cruising around, and it would bog a little as if the choke were on. I pulled over to check out a hole in the trail, adn once I stopped it revved up fine and really quick. not 2 minutes later I go to kick it and it wont roll over.

Once I get the top end apart, there are fragments of a piston skirt all over inside and they are blocking the crank from moving! The inside of the cylinder looks perfect, and the sides of the piston are in great shape, as are the rings. I cleaned out the bottom end and all bearings are in great shape, proper tolerances and wear patterns, and now everything moves as it should. I have no clue as to why this happened, and I doubt it has anything to do with the oil injector because the cylinder and piston sides do NOT have scuffs or any other irregular wear on them. ANY clues at all?

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Typically if the front/rear piston skirts break off, it's a loose bore. If the exhaust side gets stuck and scrapes the cylinder wall, it's from overheating. If the spark plug melts the top of the piston, it's running lean. If the piston broke otherwise, it is usually from too many hours on it.

Even a low performance piston needs replacing at about 60 hours. Hints that it's time for a new top end would be hard starting, fouling plugs, loss of power and that you can't remember the last time you did a top end, which is very easy to do on a Blaster. :banana:

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