# Yamaha 15 HP Four Stroke



## lakeida (Feb 8, 2010)

I am looking into buying a 2001 Yamaha 15 HP Four Stroke, and hope to be powering a Lowe 1448M jon.
My question is will the 15 HP be adequate to power the boat with a deck and floor I plan on installing in the future?

The other question is the motor has been used on and off on a dingy in saltwater I assume, and I am a little skeptical as to the maintenance the motor has received being a dingy motor, (flushing after use, preparation for prolonged storage, etc.). Besides a compression test and a test run, is there any other precautions I can take in order to insure a motor in good shape?

Thanks in advance for your advice. This site's expertise is greatly valued.


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## Whoopbass (Feb 9, 2010)

You should get close to 20 mph with that motor and a decked out boat.
Your hole shot won't be that great. It will probably take you about 10 seconds to get at WOT.

If the motor was flushed and hosed down correctly it still has a lot of life. If it was neglected I would pass on it unless it was cheap. Loosen up some of the lower unit bolts and see if they want to come out. If their stuck then forget it. If they come out and there isn't much corrosion (white dusty crap) then it was probably taken care of.

Make sure it pumps water good. Loosen one of the screws on lower unit drain screws and let a tad bit of oil out and make sure its clean. If its milky then water has gotten into it.

If your good with motors and the Seller will let you drop the lower unit then I would do it. That way you will know the shaft isn't frozen in the powerhead and you can make sure the bolts on the water pump housing will come out.


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## lakeida (Feb 9, 2010)

Thanks for the advice. 

Another question I have is what would a good standard compression test value be for that motor?

Thanks again.


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## Specknreds (Feb 9, 2010)

Check the diodes. My 25 4 stroke has several. One should be under the cavitation plate. Its a square piece that should be in good shape. If it isn't, CHECK the motor real good. This could be a sign of improper maintenance. Mine is a '04 and I'm on my 2nd set of diodes. My biggest ?? would be was the boat stored in the water? In my area, you can get just about any dealer to check out a motor for $50+. I have always worked out a deal with the seller. I agree to buy the motor and pay for the check if it checks out and you agree to pay for the check if it doesn't check out. If they are honest, they should go for it.


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## Whoopbass (Feb 9, 2010)

If 4-strokes are the same as 2-strokes then 90-110 psi range is pretty good and both cylinders should be within 10% of each other.


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## lakeida (Feb 9, 2010)

Thanks again.

Are the diodes you are referring to also known as sacrificial anodes?

The agreement for the once over by a mechanic is also a good idea.

Why do you say I will not be happy with the 15 hp, not enough for the boat?


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## Hillbillykat (Feb 9, 2010)

I have a 15 Hp mercury 4-Stroke and I'm happy with the way it performs.

It push's 2 guys and a bunch of gear at about 20 MPH.


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## MeanMouth (Feb 10, 2010)

I have a 15HP Johnson, 2 stroke on our jon boat and it does really well. It came with the boat and trailer when my parents bought the setup over 10 years ago, but we wouldn't mind having a 25hp on the back.

I think you would be happy with the 15, but ask anyone with a boat and they'll tell you that they would love more power. Buy what you can afford and enjoy your time on the water.


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## Specknreds (Feb 10, 2010)

lakeida said:


> Thanks again.
> 
> Are the diodes you are referring to also known as sacrificial anodes?
> 
> ...



Oops!!! Yes, I had diode on the brain. I spent a couple of hours yesterday searching for diodes for a board out of a welding machine for my maintenance guys.


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## lakeida (Feb 11, 2010)

Thanks for the advice, the last thing I want is to get a motor that I am going to unsatisfied with, and then have to deal with selling it.
I am going to do all my fishing out of this boat in freshwater, but speed is still an important factor.

The seller was asking for $995.


Anyway thanks again.


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