Right size prop

[CanOCorn]

I have a '02 115hp 4 stroke Yamaha and it seems to run a little high in the RPM department. It runs at 5000 RPMs when I have it cranked. Shouldn't it be at around 4000? I have an 18 pitch prop and I think it is only 14" across. Anyone have any idea on the right pitch and size to get the RPMs corrected?

Thanks,

Jason

[VMS]

If it is running at 5000 RPM's, your motor is way OVER propped. I believe the operating range for that motor is 5000 to 6000 RPM. When propping, the most desirable is to be at 6000 when you are lightly loaded.

If you are running an 18 pitch prop now, it probably has a 13-1/4" diameter. If you drop to a 15 pitch prop, you should see a gain of roughly 600 rpm.

What boat are you running?

Steve

[LMITOUT]

Yeah, that isn't high RPMs for that motor and is actually on the bottom end of the manufacturer spec....especially if running unloaded and light.

I have a 90 Yamaha which came with a 17P, four-blade prop and I was around 5200 RPM. Going to a 16P three-blade increased my RPM's about 6-700 RPM's and the boat has much better all around performance.

Are you getting the boat trimmed up all the way?

[Northlander]

What boat you have this motor on will make a big difference as well. I have the same motor on a 04 Lund Explorer 17'. Trimmed up with all my weight towards the back I get 45 mph and 5400 RPM's. Still a bit on the low side for me but I like the top end speed. Its a stainless.

I recomend you call Jay Soderbloom and explain what ya got to him and he will help you greatly. I get all my props and prop work done by Jay. Plus he is a sponsor here. www.soderbloom.com