Not turning proper RPM's

W

war623

Seaman
Joined
Apr 12, 2012
Messages
72
I just had my 2001 90 H.P. Evinrude rebuilt. The mechanic can only get a max of 4500 RPM's out of it. He said he lowered the pitch of the prop and raised the motor and now has it up to 5,000 RPM's but cavitates and I will have to back off of it.

I know this is not right and I'm asking if anyone has any suggestions. BTW, this is on a 20 ft pontoon boat.
 
S

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Not turning proper RPM's

OK what is the wot rpm and speed by gps?What prop size and style 3 blade,4 blade ,material?
There are props that are pontoon props.Usually large "elephant ear"blades.
Weight placement and and careful trim settings are critical.
As you may know a pontoon doesn't allow much up trim.Usually just set trim to the least venting.
By the way your're having venting,cavitation is a different animal and you don't feel it.
Is the motor a long shaft?
 
You must log in or register to reply here.
Top