What should my RPM be at WOT?

Elkins45

Petty Officer 2nd Class
Joined
Dec 9, 2010
Messages
123
I have a V hull 16" G3 with a 50 HP Yamaha 2 stroke. According to my instruments at wide open throttle I'm going 30 mph and revving at 4400 rpm. That's with the trim adjusted for maximum plane. I don't know the pitch of my prop, but 4400 rpm makes me think I might need a slightly different prop pitch to get the most out of this boat/motor combo. Am I right about that?
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,657
Not sure about your specific motor, but generally speaking, you should be at 5500 rpm with a light load in the boat.

Check the sticker on the motor swivel for the exact rpm for your motor.

Chances are you will only gain 3-4 mph, but by running with that prop, you are putting more strain on the motor (lugging it a little ).

Whatever the pitch is for that prop, you can safely lower it by at least two.
Example, if you have a 15 pitch prop, you could go to a 13 pitch.
If hole shot is important, or if you sometimes carry a heavier load in the boat, you could use a 12 pitch.
 

Silvertip

Supreme Mariner
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Sep 22, 2003
Messages
28,758
The starting point for this is to ensure the tach is correct. 30 MPH and 4400 rpm do not seem to mesh although 30 MPH, 16 ft boat, and 50 HP seem to be meaningful numbers.
 

jimmbo

Supreme Mariner
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May 24, 2004
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12,944
I concur about the tach, however you do need to find out what the engines WOT rpm range is supposed to be. There are too many unknowns regarding the engine to even make guesses as to your speed in regards to rpm should be. What year is the engine. Model number?
 

flyingscott

Fleet Admiral
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Apr 8, 2014
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7,985
Check your tach. I ran a 3 cylinder Yamaha 50 hp on an ss160 starcraft and I saw similar speeds to what you are seeing at 5500 rpm. The max RPM for your motor is 5500 rpm.
 

Elkins45

Petty Officer 2nd Class
Joined
Dec 9, 2010
Messages
123
Sorry to wait so long to acknowledge all the replies. I had forgotten I had started this thread. I do think the tach is relatively accurate based on my ear. It doesn’t sound like it’s at full rev for a two stroke.

It’s a 2007 and the boat is a G3 V167C. It’s a fairly light boat.
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
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12,345
Yam 2 strokes engines usually revs 5000-5500. On a light combo 30 MPH is quite possible, mine does 20 MPH with just a 18 HP while running max 5.8 K wot revs.

Happy Boating
 
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