proper rpm for 1997 120hp

[fidnee]

hello,<br /> i know many factors take into play, but what should the max rpms be on a 97 120hp force, I was out the other day, pretty calm water, 2 people on board(18 ft 1802) about 440 lbs and I was doing 30mph at about 4500rpms, does this sound about right? (not ss prop)<br /> dave

 

[roscoe]

Re: proper rpm for 1997 120hp

That engine is spec'ed at 4750-5250 rpm.<br /><br />Looks like you could use a lower pitch prop (3 inches) or the engine might need to be raised. Or... the motor may not be operating properly (carb, plugs, etc)<br /><br />Is the anti cavitation plate of the motor even with the bottom of the hull?

 

[fidnee]

Re: proper rpm for 1997 120hp

roscoe,<br /> the engine is tuned fine and i can play a little with the trim. but at that speced 4750-5250 rpm, what spped is that at?<br /> dave

 

[seldont]

Re: proper rpm for 1997 120hp

Your speed will depend on you boat, prop, and rpm you are turning. I have a 95 Bayliner Capri 1800 and at 5050 rpm mine shows about 43 mph. This is with a 19p three blade stainless steel prop. I need to raise the engine up one hole since I added the stainless steel prop. With the stock aluminum prop it would run the same speed but turned right at the 5250 rpm as spec'd.