Prop recommendation Yamaha 25LJ

[straightaxle]

I have a 25hp Yamaha 25LJ. Nymph FM164 The prop I have now is a Michigan Wheel Michigan Match 022003 9.875 dia x 9, RH. The boat come out of the hole a little slow and does not seem to hit the desired RPM at full throttle. The engine was just serviced and is in great shape. I tried the prop wizard and it did not have my exact motor, so I substituted another Yamaha 25 HP. The recommendation came out to be a 9" pitch. Does this sound right? I know 3" is a lot to change on a prop. I fish in tide waters and have to deal with hard outgoing tides, it is generally just me, and my two kids, 13, and 10. I know at some point a new motor ( boat is rated to a 50) is in order but the pocket book does not allow it right now, but I can afford a new prop.

 

[muddywaders]

S.A. I have the 30hp version of your motor and have good performance with a 9 7/8 x 11 1/4p Yamaha prop on a 14' Lund 2 guys and gear.On plane quickly and will see 30mph.The Mariner/Yamaha 25/30hp is a 500cc twin not be confused with Yamaha's 395 cc twin which I think is the one you plugged into the prop calculator.Start with the 11 1/4 and go down from there.Some shops will let you try a prop and return it.Good luck and let us know your results. M.W.

 

[straightaxle]

S.A. I have the 30hp version of your motor and have good performance with a 9 7/8 x 11 1/4p Yamaha prop on a 14' Lund 2 guys and gear.On plane quickly and will see 30mph.The Mariner/Yamaha 25/30hp is a 500cc twin not be confused with Yamaha's 395 cc twin which I think is the one you plugged into the prop calculator.Start with the 11 1/4 and go down from there.Some shops will let you try a prop and return it.Good luck and let us know your results. M.W.

I was wrong it the prop I have it is a 9 7/8x12" not a 9". Right now on tight turns the engine bogs, and is slow to regain speed. Thanks for the help. I will call around to a few shops and see if they have a few different props for me to try.

 

[turbotodd]

Max RPM on that motor is 5500. It is a torquey engine, I like them a little better than the 395cc version, but they don't idle NEAR as well as the later/smaller 395cc engines (which are twin carburetor).

Try a 9" prop. Should be close. 10" would be a happy medium between good holeshot and good top end, but would lean more toward top end speed. With the 10" you should see in the neighborhood of 23-24 mph. 9" and expect 20-22-ish. And you need a tach to make educated guesses in reference to props selection.

 

[straightaxle]

I was looking at this prop.
https://www.propellerdepot.com/solas-amita-5211-099-09