yamaha 115 4 stroke

**"G"** · 08-17-2011, 08:32 AM

Originally Posted by sliderman

As a yamaha outboard tech, I would suggest not changing props. The rpms will only go down as you load your boat with gear and friends. These 4 strokes were designed to run high rpms. If you do go to a higher pitch prop, you will probably not like the hole shot and acceleration. Another thing to consider is that not all of these motors have been equipped with knock sensors. Which is pretty important with today's fuels. And, could lead to engine failure due to over propping, a none warranty engine failure. Good luck and stay safe.

But he is running at 6200 rpms....Yamaha recommends between 5000-6000 for the 115 four stroke.

**sliderman** · 08-17-2011, 09:19 AM

Originally Posted by "G"

But he is running at 6200 rpms....Yamaha recommends between 5000-6000 for the 115 four stroke.

It's a little more complicated then just saying yamaha recommends 5-6k. That engine has a rev limiter that will prevent it from going into the danger zone of rpms. The 5-6k range is where the engine produces it's peak torque values. And, if we still had real 'gas' from yesteryear, he could run the thing as low as 5k (at wot) without harm. But the facts are the facts. That motor will last longer, provide a better hole shot, have better mid range acceleration with the prop it has. Just a reminder also. The electronics on the engine will keep it from over rev'n. But there is no safeguard built in for over propping. I suspect whoever rigged that boat & motor got it right. All in all.... the engine will turn the next size up prop. But the better choice is to keep it like it is. After all, the boat will not get any lighter. As the boat is loaded with gear, live well water, personnel, etc., the weight will be increased and wot rpm will decrease.

**warbird** · 08-17-2011, 09:52 AM

after pricing props and reading this thread i think ill leave it thanks

**yikess** · 08-24-2011, 09:05 PM

I think you will find most of us that run F115's on Aluminum boats 18' or less are using 19" stainless props that have cup like a Turbo or Stilleto. Your holeshot will be fine and your rpm's will be in line with what Yamaha recommends.
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