Compression Question re 6hp

[Anglin]

I have a '72 Johnson 6hp, (model-6R720 - serial # C36024) that has 60lbs compression on both cylinders (what should it be??)..... but doesn't seem to have the power to push a 12' Aluminum boat. It starts and runs fine but has no jam ......... Solutions much appreciated.

 

[JB]

Re: Compression Question re 6hp

Moving to Johnson Troubles, Jay.<br /><br />This forum is for answers to frequently asked questions.<br /><br />Your compression numbers seem low, but because they are equal you don't have any serious problem.<br /><br />Decarbonize your engine and check again. If they are still low (below about 90psi) pull the head and look for a blown or leaky head gasket.<br /><br />Good luck.

 

[Solittle]

Re: Compression Question re 6hp

Jay - Even if you compression were up a 6 hp may not be able get your boat up on a plane. Maybe if you & your boat are real light. A 9.9 hp will.