hi me name is Stefan and i´m in Iceland. i have yamaha tzr50 4YV AM6  it had low compression, 30psi. and i change cylinder, piston, rings, head, all gaskets, and bearings and still have low compression, any ideas

Have you checked the reeds?

no i havn´t, did use start spray in carburetor, spray is blown away from carburetor

Likely to be reeds I'd have thought.