2 Stroke Carb Jet Cleaning

[boscoe99]

Outboard Propellers, Propeller Engineering | Yamaha Outboards

[Jason2tpa]

Boscoe...see my quote below responding to 99yam

Outboard Propellers, Propeller Engineering | Yamaha Outboards

I did. The recommended props range in pitch from 13-15 at max 5500 rpms. No speed is listed. Overall, the pitch range of props for my engine is 15-21". So again, theoretically, the max rpms of 4500 im currently producing with the 21" match up. Highest recommended pitch resulting in the low end of rpm range.

[boscoe99]

I know. I just wanted you and anyone else that cares about propellers and their terms to be aware of the Yamaha documentation at the Yamaha US website.

With respect to propeller pitch range it can be whatever it needs to be. Put your motor on a 13 foot tunnel hull race boat and maybe the pitch needed will be much greater than 21". Put your motor on a large pontoon boat and maybe the pitch needed will be much less than 15". The speed will be what the speed will be. In the case of the smaller boat it might be 60 MPH. In case of the pontoon boat it may be 15 MPH.

Whatever the boat the motor is installed on, the objective is to select a propeller that will let the motor turn at the upper end of the motor's RPM range when the boat is loaded and the throttle is wide open.

Then too, there are many different brands and models of propellers that will have different qualities that different boat drivers are looking for. Two different propeller models, of the same brand even, may feel completely different even if both allow the motor to turn the WOT RPM that it needs to turn. People who are anal retentive can spend lots of time and many many dollars testing different propellers to find what works best for them.

[99yam40]

I did. The recommended props range in pitch from 13-15 at max 5500 rpms. No speed is listed. Overall, the pitch range of props for my engine is 15-21". So again, theoretically, the max rpms of 4500 im currently producing with the 21" match up. Highest recommended pitch resulting in the low end of rpm range.

OK what is the boat you have so we can look it up too.
the bulletins should show speed ,RPM, fuel burn and probably other stuff.

Hard to believe they would show your boat with different props with the same motor

[boscoe99]

I did. The recommended props range in pitch from 13-15 at max 5500 rpms. No speed is listed. Overall, the pitch range of props for my engine is 15-21". So again, theoretically, the max rpms of 4500 im currently producing with the 21" match up. Does not match up with Yamaha's recommendations. Highest recommended pitch resulting in the low end of rpm range. This is not desirable at all.

From Yamaha alone there are 51 different propellers that will fit your motor. From as low as a 9" pitch to as high as a 25' pitch.

http://yamahaoutboards.com/sites/def...e-F115-T50.pdf

From the Yamaha tune up specifications book:

NOTE: It is recommended for optimum performance and engine life to adjust the WOT engine speed to the top end of the recommended range.

From the 115 owner's manual:

Select a propeller which will allow the engine to reach the middle or upper half of the operating range at full throttle with the maximum boat load.

[Jason2tpa]

From Yamaha alone there are 51 different propellers that will fit your motor. From as low as a 9" pitch to as high as a 25' pitch.

http://yamahaoutboards.com/sites/def...e-F115-T50.pdf.

Yes, your right. There are many pitch options. I narrowed down the options by running through their selections of type of boat and performance desired. It came back with 6 options, all pitchs between 13-15.

[Jason2tpa]

OK what is the boat you have so we can look it up too.
the bulletins should show speed ,RPM, fuel burn and probably other stuff.

Hard to believe they would show your boat with different props with the same motor

Maybe I'm entering the wrong info, though it looked like a child could do it. Just in case, here's the info you asked for:
1976 Aquasport 170 (hull weight is 1100). If you're not familiar with this boat it's a fiberglass vhaul. It most closely resembles the yamaha option of "bay boat". 30 gallon fuel tank. When asked the desired performance I clicked on "top speed/max speed".

Let me know what result you get. Thanks.

[Jason2tpa]

Under the section 'current pitch and rpm at WOT' I've been entering 21 & 4500. I assume it's taking into account that the 21 is ONLY getting 4500 and it should be higher.

So when it spits out it's final recommendations the pitchs of the 9 matches are between 13-15. I assume it's doing that because decreasing the pitch will increase the rpms. I don't know the intelligence of the website.