Dedicated To The Smallest Of Skiffs banner

Compression check results

2629 Views 12 Replies 5 Participants Last post by  fsae99
Hey gurus!

My 2005 30 hp Johnson 2-stroke with electric start was making a strange grinding/clanging sound at high RPM or in the mid-range under load (plowing or turning while trying to get on plane).

I did a compression test today and got an equal 90 psi in both cylinders. I was expecting to get closer to 100, but they're both equal and it doesn't seem terribly low.

My owner's manual says nothing about cylinder compression.

How do these numbers sound?

BTW, when I pulled the cowling cover off I noticed that the starter pinion was engaged. It is showing a small amount of rust in the gear teeth. If this is not disengaging after the motor starts, I'm thinking it could be the culprit.
1 - 2 of 2 Posts

· I Love microskiff.com!
Joined
·
611 Posts
Was that CC done with throttle open or closed? My Johnson manual say to preform CC with throttle WFO. Just for grins, I did CC on mine a while back and there was 25PSI difference between throttle WFO and closed.
 

· I Love microskiff.com!
Joined
·
611 Posts
Ha Ha, I thought the OP might not know what WOT was but would surely know WFO.

"Just usually a drunk poker run guy or at the Sand bar. " I have resembled that remark in the past.
 
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top