compression-how much?

[bluebunnyss]

I have a mid 80's 6hp Johnson. What is the compression it should have?

 

[jonesg]

Re: compression-how much?

it should have the compression its got.
whatsitgot?

 

[Rick.]

Re: compression-how much?

Your looking for the numbers to be matched, or almost. Within 10% of each other seems to be acceptable to most on this forum. OMC never published compression numbers and it can change from one gauge to the next so no one really knows. The higher the better but over 90 would be O.K. to me. You can so a seafoam treatment after you check it and see if that brings it up. It sure did for my 4HP. Rick.

 

[bluebunnyss]

Re: compression-how much?

Thank you

 

[jbjennings]

Re: compression-how much?

Everyone, including me, loves to argue about compression figures which as Rick already stated, were never published. If I might ad, your motor will probably run o.k. down to about 70psi, but I like to see mine with about 80-85psi or more. I personally, have never been lucky enough to get an OMC motor smaller than a 10hp with more than 90psi. As was said, the obvious indicator is that the cylinders have close to equal compression. Compression gauges are notoriously inaccurate, seems like everyone gets something a little bit different. (I don't---my readings are always PERFECT---it's everyone else's that are wrong!!!)
JBJ