max rpm?

[DJ87]

Hello all,

I have a question about my 1987 force 125 max rpm. On the motor it states max rpm to be 5,000 rpms, but does this mean max safe rpm or is this refering to redline?

 

[Frank Acampora]

Re: max rpm?

You misread! The engine produces 125 horsepower at 5000 RPM but the wide open throttle RANGE is 4500 to 5500 RPM. I regularly run an older 125 at 5900 RPM with a special cleaver prop. Since the stroke is a paltry 2.80 inches, that engine would probably be good for well over 6000 but unless you were in full race mode, you would not want to go much over 5500. Engine efficiency and prop efficiency drop.

 

[jerryjerry05]

Re: max rpm?

With the proper load and the correct prop.You should max at 5500rpm.
Load:2 adults 1 kid a cooler and gear and 1/2 tank of fuel.
Everyone has a different load.I sometimes carry 4 adult men and 2 coolers and about 35 gal of gas and lots of fishing gear.Other days just the wife and I and a cooler.
Figure out the normal load and go for a ride.Run at WOT and see what your RPMs are.
Then go from there.5500-6000 get a different prop.Say from a 17 to a 19.
5000-5500 go down from a 19 to a 17.J

 

[DJ87]

Re: max rpm?

wow jerry and frank,thanks for the info.I will be honest, last time i took it to the lake after finally finding a 20 pole tach i was nervious to run it ever 5,000 just because i was so uncertain. I dont know what it will rev to full open but at 5,000 it felt like i had a good 1/4 inch more to go on my throttle handle. Im running a stock prop i bought on iboats but it seems like with 2 people and 20 gallons of fuel i can only go about 28 mph. Funny is i can still pull my dad out on a single ski! im wondering if i should get more comfortable with how a force sounds at high rpm and maybe find a prop that will let me go a little faster? I ski and fish on a 24 mile lake

 

[jerryjerry05]

Re: max rpm?

Like I said,go for a ride and see what it will do at WOT.Then adjust from there.How big is your boat? Get a hand held GPS to measure the speed.Not all boat speedos work right.
Do that and post again.J