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Yamaha MX & Off-Road Dirt Bikes
yz125 eating pistons
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[QUOTE="perrytime, post: 682061, member: 34521"] 1997 yz125, purchased used, after a few months, top end job needed, piston was so loose in cylinder, shop sent cylinder off for re-finish, turns out it was over bored, 50?. special wysco piston needed. Ring gap filed to be in spec. New bearing on piston, no play in bottome end of connecting rod. after a couple of hours use after careful break in, sounded funny, pull head, piston and cylinder head looks like asfault. shop says something got in or was detonation, second piston installed, carb richen'd, timing light on running engine shows 25 deg BTDC, spec is 32. After 20min of low to medium riding, smoking heavy, indicating pleanty of gas and oil, engine stops, compression is down to 60, and piston top is again rubble. what could it be? I am wondering if head has been shaved and compression is too high? Is there a way to tell? Can a compresion test when i get another piston in be too high? Could iginition moduel be doing funny things to timing that didn't show when I checked it? At my wits end how to help my son. [/QUOTE]
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Dirt Bike Discussions By Brand
Yamaha MX & Off-Road Dirt Bikes
yz125 eating pistons
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