Yamaha 50hp will not rev beyond 4100rpm

[stuart100]

2001 Yamaha 50hp engine running well, starts on the button, but does not develop full power and will only rev at about 4100rpm, on Avon Searider 13ft
Sometimes on start up will run at 4600 but after 30 seconds drops back to 4100rpm. Mechanic has checked compression, fuel suppply Etc.Etc. Very clean engine with very low hours only used for a week in summer. Was not used for a number of years.

 

[robert graham]

Re: Yamaha 50hp will not rev beyond 4100rpm

Probably dirty carbs, have they ever been cleaned? If carb jets on one or more carbs is partially plugged, then it would do what you describe. Better check it out before plugged carb/lean fuel mixture fries a piston. Good Luck!