compression variances

[dpb1122]

My 6 cylinder Yamaha 150 HP fuel injected 2 cycle has compressions from 135 to 110. Mechanic says they should be closer to each other, perhaps 10% max variance. What difference does it make - if any.

Thanks...Don B

 

[JB]

Re: compression variances

Ahoy, dpb.

Welcome to iboats.

At the least it means that the cylinders won't make equal power. At worst it means one cylinder is near failing. The lower psi suggests carbon (too high to be broken ring).

Do a decarbon job on it and test compression again.

Let us know what you find, and good luck.