What should compression be 1989 Yamaha 200 hp??

bowhuntrrl · #1 March 29th, 2003, 11:56 AM

I'm looking at a 1989 200 hp yamaha outboard. The compression is fairly even 110-120 on all cylinders. That seems a bit low to me. Does anyone know the spec for what it should be ??? TIA.

bowhuntr

JB · #2 March 29th, 2003, 12:21 PM

Howdy, Bowhuntr.

That is fine compression.

Anything over 100 psi is okay, but the important number is the difference between high and low cylinder, should not be over 10%.

Good luck.

Capt Ken · #3 March 30th, 2003, 03:43 AM

Sounds good to me also. Remember that cranking speed is in direct relation to compression. If the battery was not real hot, it can result in a lower compression reading. Once had an engine that the first cylinder checked fine and the cylinders got lower as I went. Battery was getting weaker and affecting the cranking speed.