So I am working on a friends ex J650 and got a compression testing kit to check the compression. I’m doing this because I’m having a problem getting number two cylinder to fire.
So I bought a compression test at Harbor Freight and brought it home and used it to check the compression. The compression I got from all four cylinders on the gauge only read between 60 and 65 PSI. I thought this is impossible because engines need bit over 100 psi to run.so I felt the compression tester was faulty and returned it and exchange for an identical one. so I felt the compression tester was faulty and returned it and exchange for a identical one. So I did the test again using the newer compression kit and it’s doing the same thing. Only giving me a reading of 65 psi. Now I am doing this while leaving all the spark plugs in the engine, but taking the spark plug wire off of them. I didn’t remove one spark plug and put the kit into the hole. So and made sure it was a tight fit. So I turned the key on and hit the starter and let the engine turn over when it would build no more pressure. And that pressure was 65 pounds. What’s going on here? I can’t imagine that’s the actual pressure as the engine does seem to run fine except for number two cylinder. All of the cylinders are giving the reading in the 65 pound range . Thanks for any help.
