Loss of power above 3500 RPM

[Robalo Bill]

Hello. My 24' grady white, purchased this spring, is powered by 2 1989 140 hsp evinrudes which ran well until last week. Now as I accelerate, the port engine tops out at 3500 RPM while the starboard continues to go to 4700. Motor seems to run fine at neutral and slower speeds. Changed plugs, switched plug wires from good engine to bad, but top end RPM problem persists on port engine. <br />Would appreciate any help.<br /><br />Bill

 

[Joe Reeves]

Re: Loss of power above 3500 RPM

Compression = 100+ psi on all cyls?<br /><br />Spark (with s/plugs removed = Jumps a 7/16" gap?<br /><br />The timer base under the flywheel = moves smoothly throughout its entire range and does not stick?<br /><br />If the above checks out okay, especially if the engine has been sitting for awhile, I'd suspect that the carburetors need cleaning and rebuilding.