Ok im new to this rotary motor. What should the compression be on a 88 rx7 GXL. And do you need a special compression tester?

 

The compression should be between 85 to a little over 100. 85psi is like the min and 100 is new. You do not need any special compression gauge can pick them up at you nearest auto part store for around $40. Just disconnect your CAS (crank angle sensor) and your fuel injection fuse in the engine bay and pull out both top spark plugs. And make sure you take the valve out of the testor for a good reading. Hope this helps.