Yamaha C90 1997 RPM Range

[msd58]

Wwhat is the recomended RPM range for a 1997 C90 Yamaha? I am running this around 4300-4500 RPM @ 25-28MPH I know it has more to go but I don't want to over do it. Its on a 17' Montauk B/W.<br />Thanks

 

[jim dozier]

Re: Yamaha C90 1997 RPM Range

I don't know the exact number but its probably around 5500 rpm. You are well under it. It does not hurt an outboard to run at full throttle (WOT). Make sure it will hit around 5500 at WOT, if not you need to change the prop so it does and you don't lug the engine.

 

[rodbolt]

Re: Yamaha C90 1997 RPM Range

full throttle range is 45-55 hundred RPM.<br /> yamaha recomends propping to the high end of the range.<br /> good luck and keep posting

 

[msd58]

Re: Yamaha C90 1997 RPM Range

Do that mean I should go from a 15" pitch staineless to 17"?

 

[Paul_Dublin]

Re: Yamaha C90 1997 RPM Range

No. go for a lower number.<br />If you're a 15", drop to a 13".<br />Each inch adds (or removes) about 200RPM, so you should reach 5000 or more with the 13".<br />It's like having your car in a lower gear.<br /><br />Shouldn't effect top speed, but will increase acceleration.

 

[msd58]

Re: Yamaha C90 1997 RPM Range

"I am running this around 4300-4500 RPM @ 25-28MPH I know it has more to go but I don't want to over do it."<br /><br />I can run well past 5000RPM now thats why I asked about going to a 17"

 

[jim dozier]

Re: Yamaha C90 1997 RPM Range

As long as you have open and relatively calm water I don't think you are even close to overdoing it at 28mph in a 17' boat. I've windsurfed faster than that. Open that puppy up and let her breathe.