Hi Everyone

When I got this DT to restore, previous owner told me it had seized, so he did rebore with oversize piston and rings. He says it ran for a week and lost compression. But if I feel resistance on the kickstart it seems to have pretty good compression. Could I get some fuel in and try start..or could I cause damage?

Not a lot of information in your post, but what's the worst that could happen? just bung some fuel in the plug hole and see what happens, you should get a moment of running which will tell you that it does actually go and then you can fix it knowing that the engine is sound, could be anything really from what the previous owner said. Others on here will come up with about 400 reasons for loss of compression most of which are nothing to worry about. Good luck with your test run.

Nothing you could make worse thats for sure.

These engines are really solid and being a 2stroke there few moving parts. Give it a go i say.

Should have mentioned he says one of the head bolts refused to tighten properly.

Ok big difference.

Easy enough though. Take the exhaust off then remove the head and replace the stud.

Job done.

might be stripped though youll have to find out whats wrong

If the stud's stripped, just replace it, if the thread's gone in the casing you'll need to helicoil it, or possibly tap it to a larger stud size if there's enough metal. Either way, it should be a simple fix.

Found the culprit..head and barrel off..found top piston ring broken into pieces..piston slight damage..will replace both. I`m guessing previous owner did not take it easy after the rebore. Luckily the bore looks ok. Are pirate piston & rings ok?

If it's been rebored have the ports been chamfered ? If not this can cause the rings to catch and break.

Actually just read about this on this forum while browsing a DT250 restoration..maybe this is what happened..not sure if its been done. Better make sure before I install new piston.