losing rpm

[David Butler]

i have a 75 hp mecury when trimed out would always run 5150 rpm at 42 mph. lately can only get 5000 and about 40 mph. Question for you guy's in the know is spark plugs? or carburetors?

 

[Chris Leiting]

Sounds like a typical summer performance loss... 150RPM is not very much of a loss... you may have a fouled plug or a pluged carburator but.. the question is does the motor sound like it's missing at idle?

 

[Staci Matheis]

Could also very easily be a dinged prop.

me!

 

[Chris Leiting]

Dinged prop would not cause loss of RPM it would cause loss of top end but no loss in RPM