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

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    Thumbs up Interest in new 3 cylinder drag rules..motor alterations and mixing manufacture parts

    The first interest I have is building a 49 cubic inch out of the 3 cylinder 40/50 hp Yamaha block.
    How do you do it?
    Second is matching up a 3 cylinder OMC powerhead with a 40/50/60/70 1:64 gear case.
    What is the best way to do it?
    Cut and weld mids- use an adaptor plate above the gear case- use a custom powerhead base plate on the Mercury mid?
    Any pictures?
    Thanks
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    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.

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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.
    Those Tiller guys know what is going on with drag rules (Mitch Hardee, Kent Foreman, Bill Kopod).

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    2010 SRG 3 CYL CHAMPION 88workcar's Avatar
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    Why limit yourself to 49ci? And no sir it will not be superior. I have a few 52ci spinning 8400rpm and making gobbs of power, a hot 42 don't stand a chance to that.
    Helping folks out around the globe.

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    Quote Originally Posted by 88workcar View Post
    Why limit yourself to 49ci? And no sir it will not be superior. I have a few 52ci spinning 8400rpm and making gobbs of power, a hot 42 don't stand a chance to that.
    I already have several 15 inch 70CES motors. The 49 modification provided it still used the 50 hp crank should have an advantage. The lighter weight of the motor and the smaller gearcase would also help. Have you ever seen a 49 ci mod 50 yamaha? I have not and I question if there is one.
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    2010 SRG 3 CYL CHAMPION 88workcar's Avatar
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    I have only heard of a 49ci 40/50 Yamaha. I also heard that you can go bigger but 49 was safest. Build it and see. A CES shares the lower with a 40/50. So you still have 52ci on top of the same lower. The lighter part may be worth some but so are 3 more cubes. You have to build it to see lol.
    Helping folks out around the globe.

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    need to make a 3 cyl out of the sst45, then you have 100hp with stock porting at 7000

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    Quote Originally Posted by 88workcar View Post
    A CES shares the lower with a 40/50.
    Not true. The original 3cyl 2-stroke 40/50 (700cc) lower is shorter in length and height, and has a smaller (diam) driveshaft. The casing will also not bolt up to a 70 (850cc) mid. The 70CES uses the same lower (aside from gear ratios compared to some) as the 48/55/60 2Cyl and some versions of the 50G (and some other 850cc) engines. The newer 4-stroke style 50 lower casing does bolt up to the 70CES (and standard 850cc 70) but the driveshaft splines are incorrect from the factory.

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    The 49 Yamaha would be interesting to build. The CES does not share the 40/50 gearcase, it has the 55 case. Making a 3 cylinder SST45 could be possible. I have seen mod 4 cylinder motors in snowmobiles made from two 2 cylinder motors. Years ago some mod outboard racers mounted 2 powerheads on a single tower.
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    It would mean making new 3 cyl crank and see if you could swing that in 56 case?
    Thats the engine omc should have made as yam just marched in with bigger tripples and took tons of market
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