Help With Identifying Prop Manufacturer

[Jason2tpa]

Hey guys. I'm helping out a friend by trying to figure out the manufacturer of his prop. This is what is known of prop:

* SS
* 13 x 17 – K
* 3 Blade
* Standard Rotation
* 607 (stand alone number stamped on outer hub)

Engine is a 1987 90hp 2 stroke. The previous owner of this engine stated he got the prop from yamaha, yet the yamaha name or any other identifying marks are not labeled on prop.

I did notice on the picture of a yamaha label below that the letter "– K" is listed directly after the diameter and pitch. Is the letter "– K" an identifier for yamaha props?





Also, I need to confirm this engine is a 15 spline. Can anyone confirm this?

[pstephens46]

I hate to refer anyone here elsewhere....but sounds like a good question for the
Propgods.....they might like a pic. Having said this, who knows?

[Jason2tpa]

I hate to refer anyone here elsewhere....but sounds like a good question for the
Propgods.....they might like a pic. Having said this, who knows?

I actually just posted a thread on THT a few minutes ago. I know they are on that forum.

I also just found a yamaha prop sheet online. They make a K series 13 x 17 prop for a 4.25 gear case, and his gear case is the same. So i'm starting to lean towards this prop being a yamaha.

[pstephens46]

10-4........

[pstephens46]

Don't think my prop has Yam markings either. Must investigate...

[Sequoiha]

Yes it is a Yamaha prop.

[boscoe99]

A letter code denotes which family of Yamaha motors the propeller will fit. K means it will fit a 50 thru 115 HP motor. KL means it will fit a 50 - 115 counter rotating motor.

Yamaha is bad about not marking all propellers. Some will have a letter, some won't. Some will have a part number. Some won't. Some will have the diameter and pitch. Some won't.

http://yamahaoutboards.com/sites/def...ber%202013.pdf

[boscoe99]

Also, I need to confirm this engine is a 15 spline. Can anyone confirm this?

Count the splines on your S115. I am guessing there are 13. I think the 150 HP and up models use 15 splines. But my memory is not what it once was.

[Jason2tpa]

Count the splines on your S115. I am guessing there are 13. I think the 150 HP and up models use 15 splines. But my memory is not what it once was.

My engine has 15. But I have no idea how many an '87 90hp has.

[boscoe99]

My engine has 15. But I have no idea how many an '87 90hp has.

Same propeller used on a 90 is used on a 115. So I am guessing that the spline count is the same.

[Jason2tpa]

Same propeller used on a 90 is used on a 115. So I am guessing that the spline count is the same.

I too was guessing, but im more confident now learning your guess is the same. Thx.

[99yam40]

if the K fits a 50 to 115 as was written, the 90 and 115 are in that range along with other motors.
so they all should have the same splines.

but we are depending on Boscoe's memory

[Jason2tpa]

My 21" pitch prop is the only prop I've ever run on my boat. I had the opportunity to trial my friends prop, the 13 x 17 prop mentioned in this thread. Right from the beginning of the trial with the hole shot was a dramatic difference. The 17" jumped out of hole far quicker, but the rpms were 4800-5000 as the boat leveled (spec rpm range for my engine is 4500-5500).

At WOT I reached top speed of 41mph and 5700 rpms. I reach the same top speed at WOT with my 21" pitch.

Another dramatic difference was the cruising rpms. With my 21" I'll cruise at 3700 rpms with a speed of 30-32 mph. At this rpm the engine has the sound as if it's not "working hard", as in it doesn't have the high pitch sound you'll hear when at or near WOT.

With the 17" the rpms were 4500-4700 to maintain cruising speed of 30-32mph, but the engine sounded winded out, much higher pitch sound.

And that was the most noticeable difference between my 21" and the trialed 17"...the engine sound. From 4500 to WOT the engine just sounded way different, much higher pitch sound. But maybe this is because I've only heard my engine run with the 21".

Either way, the 17" just winds up too much. Top end rpms were above spec range of 5500. And I didn't like how high the cruising rpms of 4500-4700 were at just to maintain speed of 30-32. When I maintained rpms at 3500-3700 it felt like boat was struggling to stay on plane. Which with my 21" I can stay on plane with rpms as low as 2100.

So at least now I know a 17" pitch is too low for this boat (or at least a yamaha K series 17"). An 18" or 19" should do the trick.