Low compression in 1987 Yamaha 115hp

[ozkor]

Hi Just wondering if someone had some input for me on this one. I warmed up my motor and ran compression tests on all four cylinders. #1 65 psi #2 65 psi #3 65 psi #4 63 psi. Its a brand new gauge -its a cheap gauge from a good shop so I think it should be a reliable gauge. The motor reaches 5100 rpm and at least 69kms per hour. Seems to run smoothly at all rpms. Idle sounds like a typical two stroke perhaps missing a little but hard to tell but runs perfectly. I guess I am wondering If I have bought something that is about to die out and shouldnt bother spending any money on it or if it is normal for this type of motor. Any ideas would be appreciated.

 

[racerone]

Test with another gauge !!!!!!!!!

 

[robert graham]

Since the readings are all about the same, I'd say that was a good thing and your "cheap" gauge could be off. I also doubt that you have a problem, but you could invest in a quart of Yamaha Ringfree and run a tank of gas through the motor with the "deposit removal" dosage to remove any carbon on the rings or in their grooves....then re-check your compression.....You might start using the Ringfree on an ongoing basis to help reduce/prevent carbon....

 

[ozkor]

Hi Thanks for your input appreciate it. Will get some ring free and give it a go as well.