No compression on Dirt Bike (92' Honda MTX80 R2 HD 09 2 stroke)


I recently acquired an old bike and am not sure of its maintenance history.


The bike will not start, I took out the plug, looked fine, sparks fine grounded against the frame.


I also did a compression test, and, quite mind blowingly, the compression barely even registers, is probably at about 10 PSI (the tester doesn't even have markers that low).


The owner said it was running fine on a push start weeks before.


I'm wondering though, is the (near) zero compression a sign of anything else? It seems absurdly low. I can pull the kickstarter down with my pinky.


Does the lack of compression 100% indicate that it needs a top end rebuild or are there any other things I should check first before going through with that?


I also can't even get the clutch to disengage, not sure if it's cold oil, from sitting in storage or what, but I will probably need to overhaul the clutch and file down the basket etc.


Any tips appreciated, I am somewhat new to motor work!

You've already found the problem. I'd be *HIGHLY* surprised if it was able to run with only 10 psi of compression. Maybe a sputter here and there, but there's no way it could "run". The seller was lying to get you to buy it. It needs a piston and rings at the least. Once you open it up, you'll see if it needs a cylinder as well. Nice thing about 2 strokes, is just pop the top off the motor and look inside. Takes just a few minutes.

Edited by yellowdatsun

I've ordered a service manual and am just waiting for it to arrive, so it's almost 100% certain that the problem is in the top-end then when one has low compression?


The owner said she is able to rollstart it in second going down a hill, but I can't imagine that if she's been running it like this for some time that it could be any good for the engine if a ring was worn or something.

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