Twin 150 Yamaha compression

[jasoncooperpcola]

Today i checked compression on both engines.

The port engine has the following compression: #1- 113 #2- 120 #3- 115 #4- 119 #5- 115 #6- 120

The Starboard engine has the following compression: #1- 115 #2-105 #3- 119 #4- 120 #5- 115 #6-120

Should i be worried about the 105 in the starboard engine? That is the engine thats being troublesome.

Also checked lower units today. Both units turned about 1 1/8th of a turn with two full turns of the flywheel. So lower units is not my problem. Is there any other reason why the starboard engine will only reach 4500 rpm? I'm thinking it may be a carb issue. It doesn't worry my dad though. I just want to see what the boat is capable of doing.

[Blue_Runner]

Those compression numbers look fine to me. I don't think that is your problem but what do I know.

Wait for a true motor head's answer.