Modifying a 2001 Yamaha 25hp four stroke?

Discussion in 'Boats, Blinds, & Gadgets Forum' started by StumpJumper, Feb 9, 2018.

  1. StumpJumper

    StumpJumper Refuge Member

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    Is there any way to up the hp in this motor? I know some 25's can be modified in to 30's, but I'm not sure if it's possible on this motor.
     
  2. Tuleman

    Tuleman Elite Refuge Member

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    Might be tough.
    Many of the old 2-stroke outboards used the same unit (powerhead and lower end) for several different horsepower ratings; the difference being the swappable components like carb, exhaust reducers, ignition boxes, etc. The newer Yamaha 30hp outboards are entirely different motors than the 25hp. Do some research on the 2001 25's and 30's; if they are the same displacement then you might be able to do some parts swapping. If they are different displacements, then you are out of luck. One easy check is to compare the weight's of those two; if they are the same, then you can bet they use the same basic motor package and parts-swapping would be easy if not cheap.
     
  3. mmayes

    mmayes Diver Forum Mod Moderator

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    I have a 2000 Yami 25 4 stroke and asked a while back and was told nothing you really can do. So if you find out different please let me know

    Mayes
     
  4. bullpinnie

    bullpinnie Elite Refuge Member

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    I'm not too, mechanically inclined, but this, I know for sure. Once guys start modding their motors, they lose reliability. I have at least a dozen friends that were hell bent on modding their motors, and all seem to become "basket case" motors afterwards. I had a stock 90's Yamaha 25 for at least 20 years, and never had an issue beside replacing impeller, and water pump. my advice: if you are good at working on stuff, have at it, otherwise leave it alone.
     
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  5. Phytoplankton

    Phytoplankton Elite Refuge Member

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    Call Hydro Tech Marine Performance, if it can be done, they'll know how to do it, but it won't be cheap. Chances are you're better off trading the motor in on higher hp engine. For 5 hp you're only going to get a couple MPH, you might be able to achieve that by playing with the set-up (engine height, jack plate, load distribution, different props etc).
     
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  6. Fowler267

    Fowler267 Elite Refuge Member

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    In need of a bigger motor . Order the smaller horsepower stickers while you are at it!
     

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