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Thread: Interest in new 3 cylinder drag rules..motor alterations and mixing manufacture parts

  1. #41
    Team Member Roflhat's Avatar
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    Wouldn't have thought a bigger powerhead would fit under a 50hp cowl, I suspect it's just a tuned 50hp
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  2. #42
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    the way I read it is they took the 50hp block done a bit of work and bumped up the hp to 75hp at the prop,
    so I doubt very much its just a 75 hp block fitting under there.
    if the 75 block was fitted then I am sure he would be claiming much higher horsepower from hydrotec ( 85 - 95 etc)..

  3. #43
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    Quote Originally Posted by Hounddog View Post
    No replies yet so I am guessing there is no 49 cubic inch conversion from the 42 cubic inch 40/50 hp Yamaha. Too bad because it would certainly be superior to the 52 cubic inch Yamaha and there are lots of 40/50 outboards available.
    This thread is about the 42 mod to 49 conversion. It is said to produce horsepower in the 75 range. I posted the Hydro Tec motor since it was posted in the ad at 75 hp. I wondered if it was a big bore mod 50 Yamaha. It would be difficult to get 75 hp out of the 42 cubic inch . If it is 75 hp many of us would want that motor.

  4. #44
    Team Member 88workcar's Avatar
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    Love reading the old stuff, I have since built a 42ci mild build. It made 69hp and spun to 8200. Stock bore stock stroke, If I spend a little time on r&d there is more there.
    Helping folks out around the globe.

  5. #45
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    Quote Originally Posted by 88workcar View Post
    Love reading the old stuff, I have since built a 42ci mild build. It made 69hp and spun to 8200. Stock bore stock stroke, If I spend a little time on r&d there is more there.
    It is impressive how the 3 cylinder 42 cubic inch Yamaha and especially the 50 hp Tohatsu have broken many of the speed records in the last few years.
    In 2013 a 50 hp Tohatsu raised the speed record in T750 over 10 mph to the current record of 66.69 mph.
    In 2015 a 50 hp Tohatsu set a new speed record in SLT Pro Stock at 62.99 mph.
    Even more impressive in 2015 a MOD 50 Tohatsu set the MOD750 SLT record at 71.35 mph.
    Over the years we have read about 70 hp carbs, custom cylinder heads and custom tuners being used on these motors.
    But, none of those motors got close to 71 mph.
    I for one would be very interested hearing from people in the know just how they do it.

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