Max rpm

[cousineddie]

I have a 1995 Force 90 HP with a13" x 19 P prop on a 1995 Skeeter SS-140 bass boat and was wondering what my max rpm should be? I've clocked it at 40mph with my gps but my tach was'nt working. I'm trying to figure out if I have it running at its max rpm or if I need to reprop it. It comes on plane fast and seems to have plenty of power. I plan on getting the tach working this weekend to try it again.

 

[jerryjerry05]

Re: Max rpm

Need to know what rpm's are.That is the only way to check pitch and prop size.Jerry

 

[ck85abc3]

Re: Max rpm

If you have gps speed, pitch of prop, approximate prop slip, and gear ratio, shouldn't you be able to calculate rpm?

I don't think it matters, because he should have his tach installed soon.

 

[Frank Acampora]

Re: Max rpm

If the 140 on your Skeeter indicates a 14 foot boat or even a "big" 14 footer like 14 foot 10 inches, I would expect at least 45 and maybe even 50 MPH at top end, given correct prop and trim.

I have a light flat bottom 14 footer with a 90 and it goes 56 at 5600 now with a 13 X 21 uncupped stainless prop. When I test the racing props I recently bought and jack up the engine, I expect to get better than 60 MPH--and that's a stock 90 with a 2 to 1 lower unit.

 

[cousineddie]

Re: Max rpm

Frank its a 17 foot fiberglass bass boat. I think 40 mph is about the limit with this motor.

 

[roscoe]

Re: Max rpm

Try for 5500 rpm, should give you the best hole shot, and near maximum speed.

4900-5600 rpm is good.