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  1. #1

    how much compression

    can you get on a set of gp1300R cylinders and still use 91 octane gas ? we only have the 91 stuff out here in the golden state.My friend has to use race gas and its a HUGE PIA.

  2. #2
    20 feet Boy's Avatar
    Join Date
    Jul 2010
    Bend OR
    185 psi and higher you will have to do higher octane. It border line.

  3. #3
    Yamaha artisan Cutlass's Avatar
    Join Date
    Oct 2010
    Madison, WI, USA
    And most rec ski users who bump up the compression stick to 150ish and use premium.

  4. #4

  5. #5
    i see some 1200 riva heads on here. will they work with a 1300 ?

  6. #6

    Join Date
    Jan 2006
    Texas City, Texas
    Quote Originally Posted by strokersquid View Post
    i see some 1200 riva heads on here. will they work with a 1300 ?
    The domes would have to be reshaped.

    Your two best (and cheapest) options would be to have your stock head reshaped and set up for 92 octane gas (read at Other professional builders perform this mod (Jim's performance, Lowell, etc).

    Another method is simpler. The stock head gasket is made of 3 aluminum layers. Some guys just remove the middle layer, reinstall the gasket, and torque back to specs. This bumps their compression slightly. You may have to look into readjusting your jet settings. Read up on this one. I do know that this is done, but do not know the details.

  7. #7
    thanks, we do this on 2 stroke bikes and i didn't remember it ! in fact we often just use one layer.

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