1999 yamaha 200hp compression

[godevil1]

My motor is a carburated model. The port side from top to bottom reads 104,115,114. Starboard reads 121,120,118. Recently I ran some yamaha ring cleaner thruough it. anyway, I lost about 4 mph on top end. All other ranges run great. Any ideas?

 

[Genesis]

Re: 1999 yamaha 200hp compression

Yeah, 104 is out of spec; you have a low hole.

Its not horrible, but 10% is the usual variance that is allowed.

I'd run a tank of SeaFoam/Gas (pony tank, 1 can seafoam to 1 gallon of gas) through it and see if the situation improves (this will free up stuck rings); if not then either live with it or tear it down. If its running ok otherwise I'd probably leave it alone, but be prepared for a potential "bang" somewhere down the road.

Also, check the cooling system - the top cylinder being low is not unusual if the cooling is compromised as the top cylinders will run hotter (higher, less flow through that part of the jacket) and this results in excessive wear.