Re: Top speed with 18hp Evinrude on 14′ aluminum

[wiscoboater]

One other thing to think about Stephen. Just because it makes compression when doing the compression test, whats not being measured is "blow by". As was stated earlier in this thread, a leak down test will most likely reveal that it is not holding that cylinder pressure for the complete combustion stroke. That is where the significant power loss comes from. The pressure is leaking past the rings.

Also, be very careful when buying powerheads from Ebay. They show you a compression gauge pegged at say 120lbs. and state the power head "has great compression". Last winter I had a 66 FD 20 with 120 on top cylinder, 60 on the bottom. If i put about a teaspoon of 2 stroke oil in that bottom cylinder I could get it to read 95psi. on the gauge. You see where I’m going with this? Buyer beware.