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Thread: Tohatsu 50 mods

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    Team Member Roflhat's Avatar
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    Default Tohatsu 50 mods

    Planning some mods this summer, got Yamaha 70 carbs to go on, need to open up the reed block for them too. Got a Mikuni fuel pump to put on as well which is hopefully more reliable than the standard tohatsu one.
    Was going to modify the exhaust tuner as well, open it up a bit and cut 25mm off the end. Has anyone else done this? How do you get to the exhaust tuner?

    Also read online that the flywheel ring gear can be removed so going to look into that. Or if not then maybe lighten the flywheel.

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    Team Member Roflhat's Avatar
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    anyone know roughly a big a job it is removing the crank, welding it and putting it back in? how many hours/days, just so I know what to expect.
    Cheers

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    Team Member ice_spy's Avatar
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    70 carbs will drop bottom end power. Not enough air/fuel speed at lower rpms so the mechanic tells me.
    Welding the crank, plan to rebuild also, as once welded, the crank is throw away item.
    drilling some relief holes through the leg, where it narrows above the pump, helps them breath a little more.

    I think afterrmarket reeds, correct jetting and a little more compression via skimming the head is a good start. (check your class regulations)

    Remember speed and performance can be had from a new prop. Now thats got to better than shortening the life of your motor by over modifying it.
    The race never stops

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    Team Member Roflhat's Avatar
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    Hi mate,
    thanks for the reply.
    I've got yamaha 70 carbs already so they're going on. I've been advised on jetting so will get that done too.
    The crank is going to be welded and then balanced along with the flywheel. I've done the above prop exhaust mod (relief holes).

    Has boyesen reeds in it, will be getting the head shaved as well, thinking 1mm off?
    I'm not using the boat for racing so no regulations, just learning about engines and trying to go faster.
    I've got decent props just now, although I don't have a big prop for top speed.

    Cheers

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