palanchou Posted August 13, 2011 Share Posted August 13, 2011 hi, got a 1983 yamaha dt50mx as a project.hardly any compression, so a rebore over size new piston and rings, new gaskets. still no comp. please any of you guys any ideas, thanks bill j. Link to comment Share on other sites More sharing options...
Tuesday Posted August 14, 2011 Share Posted August 14, 2011 First guess is it is just a tiny 50cc engine and the compression is just fine. Second guess is the piston barrel seal. If you stick a dribble of 2-stroke oil down the spark plug hole to coat the bore and rings. Put the sparkplug back in and turn the engine over. If there is more compression (even just at first) you have traced the problem to the piston barrel seal. A time ago I had a knobend rebore my bike engine, The tit-head bored the barrel out to the maximum wear limit.Hope this has not happened to you. Link to comment Share on other sites More sharing options...
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