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  1. #1

    1100 exhaust ports

    Ive got a 97 1100 waveventure I bought as a project. I bought a used cylinder and was checking it over when I noticed that the steel sleeves exhaust port is smaller than the cylinders exhaust ports.

    I checked the old cylinder and its the same way. I have no problem porting it too match but I'm concerned about raising the port timing if I match the upper part of the sleeve too the exhaust port and possibly losing bottom end punch.

    I assume the 1200s are the same way. My question is do most leave it this way or open them up to match? I cant imagine Yamaha has the ports too big for the motor.


  2. #2

    ports

    So I take it either nobody's noticed this before or its classified?

  3. #3
    Adam's Avatar
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    Wink

    Dont raise the port but make it wider to match the cylinder, this will give more torque without loosing power down low. Do you have after market sleeves to insert into the cylinder ? If so , you can port all three cylinders to the same dimensions before installing. You get a much more accurate job, then match the aluminium to the new port. The transfers aim too far back in the cylinders for top end,the angles can be changed to aim more to the center of the cylinder. This is why you port the sleeves first before installing them, its easier to measure the angles and get the ports perfectly symetrical.
    The aluminium transfers are notoriously poorly matched on Yamaha's,big improvements can be made here!

  4. #4
    Thank you for the reply.

    The port is about 1/8 lower into the port so its hard for me to understand why anyone would leave it this way. I am afraid of killing the bottom end , this is my first Yamaha and im trying to get a handle on what works with these. I've matched everything but the top.

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