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  1. #1
    Site Admin Green Hulk's Avatar
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    New Riva Thermostat Delete kit for SHO/SHVO engines

    RIVA Yamaha 1.8L Thermostat Delete Kit

    Allows Yamaha SVHO, SHO & HO engines to run cooler by replacing the thermostat with a specialized restrictor. Ideal for modified watercraft operating...
    RY1013-40-TR $22.95



  2. #2
    No GIO issue with this?

  3. #3
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by GPR View Post
    No GIO issue with this?

    Removing the thermostat completely, yes!
    Using this restrictor, no!

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    Is this better then replacing the svho thermostat with the other model sho t-stat that opens sooner?

  5. #5
    It cant be that easy??? Just remove the thermostat and place the plug and done? Any additional parts needed for install?

  6. #6
    Ski Hacks MG's Avatar
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    Even on a modified engine, is there a benefit to the engine running cooler than Yamaha designed it to run? JMHO, but it seems counter productive to the standard combustion and fuel efficiency process that Yamaha intended considering they want the head and cylinders to be a certain temp for optimal combustion. Also, how will the temperature of the engine ever be controlled with a stat?

    I'd like to understand this mod better. I'm all about it if there something I am not understanding here.
    Last edited by Ski Hacks MG; 05-28-2015 at 02:29 PM.

  7. #7
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by Sam SHO View Post
    It cant be that easy??? Just remove the thermostat and place the plug and done? Any additional parts needed for install?
    Yes it's that easy! remove thermostat. Replace it with this restrictor plug.

  8. #8
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by CCW View Post
    Even on a modified engine, is there a benefit to the engine running cooler than Yamaha designed it to run? JMHO, but it seems counter productive to the standard combustion and fuel efficiency process that Yamaha intended considering they want the head and cylinders to be a certain temp for optimal combustion. Also, how will the temperature of the engine ever be controlled with a stat?

    I'd like to understand this mod better. I'm all about it if there something I am not understanding here.
    Absolutely! The problem is with a modified engine the engine temps continue to soar after a prolonged wide open throttle pull and THAT is counter productive to performance as as the engine heats up the ECU pulls timing and with reduced timing comes reduced performance. Those with ViPEC, MoTeC can see this in their logs.

    You want to maintain around 165-175 degrees operating temp, even after hard WOT use. That is going to yield best performance.

  9. #9

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    The issue with the thermostat is the amount of flow when its open. My guess is that this restricter strikes a balance between the limited flow of the stock T stat and just removing the T stat which flows more than needed and cools the engine below operating temp. Obviously if you run in very cold water this would not be the mod for you.

    When running higher than stock RPM's you engine now has a lot more heat to dissipate than the stock T stat was designed for. So your engine will actually be running warmer that yamaha designed it to be and with a boosted motor higher temps on the block/heads mean higher combustion chamber temps and that can equal detonation which would be bad.

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  11. #10
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by SilentShooter View Post
    The issue with the thermostat is the amount of flow when its open. My guess is that this restricter strikes a balance between the limited flow of the stock T stat and just removing the T stat which flows more than needed and cools the engine below operating temp. Obviously if you run in very cold water this would not be the mod for you.

    When running higher than stock RPM's you engine now has a lot more heat to dissipate than the stock T stat was designed for. So your engine will actually be running warmer that yamaha designed it to be and with a boosted motor higher temps on the block/heads mean higher combustion chamber temps and that can equal detonation which would be bad.
    Very well said!

    I have one on the way for my turbo FZR. Stock thermo is too restrictive and causes increase in temps after hard riding.

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