Nowatny

Member
Jun 27, 2018
1
0
I bought a cheep 2 stroke a while back, ( 93 kx 80) and fully rebuilt it top end and bottom new seals bearings also a completely new cylinder since the old was scored, all stock OEM specs no big bore kits or anything but I put it all together and no start check compression since it seemed low on the kick starter and it was I got 75 psi from roughly 5 kicks, so my question is with a new top end what else is making my compression so low? leaky seals on the bottom end? Help!
 

Okiewan

Admin
Dec 31, 1969
29,555
2,237
Texas
Did you check it with the throttle wide open? I assume you know you got a good seal with the tester ...
Did you gap the rings?

Try this; put about a teaspoon of premix oil in the cylinder and test it again. If the compression increases, the oil is sealing the rings (meaning the rings are leaking by and need to be gapped).
 
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