I'm just going to buy this cheap set I found at Harbor Freight. Comes with the adapter I need. I'll compare my buddies to the new on and see if they have the same readings...

Compression Test Kit

 

looks like a decent kit. Id be interesting in hearing the results of comparing the two gauges.

 

just getting back to this project...I didn't buy the harbor freight tester due to poor reviews. I borrowed a mac tester instead and found the compression to be 120. I put some oil in the cylinder and got it a little higher but nothing close to the lowest allowable pressure. I just finished taking the head off and
inspecting the piston/rings. They don't look to bad but need to measure them and will probably just go ahead and replace the set. I'm probably going to do the same with the valves since I already have everything apart. The cylinder wall looks nice and smooth with no scratches.

 

A question about moto-4 80 1987. Is it a solid rear axle without any differential like lsd?
Mine always has the same drive on the rear wheels like it was in diff lock, makes it hard to turn sometimes. I guess it should be like that? Or is something broken i the back axle?

Thanks.