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  1. #1
    Site Admin Green Hulk's Avatar
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    RIVA valve train upgrade install - overview

    I'm in the process of installing the Riva valve train upgrade on my ski and wanted to show you guys whats involved.

    This is not to be a substitute for the instructions but rather a brief overview of what you can expect when doing this upgrade.

    Here are the actual instructions for using the Riva valve train upgrade tool
    http://www.rivamotorsports.com/instr...y19040_vct.pdf

    You will also need the Yamaha service manual on hand for reference.


    With the valve train upgraded you can spin the engine as high as 10,000 RPM's. With the stock valve train the engine is safe spinning up to 8500 RPM's.

    I wanted to measure any differences between the Riva springs and retainers and compared them to stock.

    Amazingly the Riva titanium retainers are half the weight of the stock ones.
    Riva's weighed in at 4 grams with stock being 8 grams





    Riva free spring height 1.570"
    spring pressure at 1.250 72 lbs
    spring pressure at 1.150 96 lbs

    Stock free spring height 1.790
    spring pressure at 1.250 64 lbs
    spring pressure at 1.150 80 lbs






    Now on to the install. You will remove the valve cover, timing chain tensioner, exhaust side chain guide and camshafts. It's EXTREMELY important that you number all the camshaft caps so that they go back in the same place.

    I highly recommend you guys prepare your work area and lay towels around the engine. The last thing you want to do is drop something down into the hull.




    Once you have the cams removed it's time to pull the spring buckets off of the springs. Use a magnet on the center of the bucket to do this.



    The reason you want the magnet on the center is because there is a shim underneath the bucket.



    Do not drop or lose the shim. Each of these buckets has to be put back in the exact same spot. I laid out all of my removed parts carefully so that i can easily put things back exactly the way they were.



    Once the buckets are removed it's time to pressure up a cylinder and start swapping out springs and retainers. I used 100 psi of air pressure.
    The Riva valve train upgrade tool is actually for both the Yamaha and Kawasaki skis. For the Yamaha ski you will use the larger hose to screw into the spark plug hole.



    Once the cylinder is pressured up you can use the tool to compress the spring and remove the cotters. This is simply done by pulling down on the handle and then using a magnet to retrieve the cotters.



    Once the cotters are removed lift the tools handle up out of the way and remove the stock retainer, spring and base and put aside.

    I pushed the Riva base washer onto a spring and then dropped it down into it's place. I then filled the hole of the Riva retainer with some grease to hold the cotters and then carefully set the retainer on top the spring.



    Then i use the tool to compress the spring while carefully using a small screw driver to push the cotters into place. Once in place just release the handle. I usually give the handle a few up and down movements to ensure the cotters are safely in place.

    As i replace the spring/retainer assemblys i put the spring bucket back in it's place as you can see here in this pic. Half of the springs have been completed in this pic.

    Last edited by Green Hulk; 12-09-2009 at 01:04 PM.


  2. #2
    Site Admin Green Hulk's Avatar
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    Once you get all the springs and retainers switched out you will want to time the cams. You do this with #1 piston on top dead center. An easy way to turn the engine over is to remove the pump cone from the pump and use a 27mm socket on a ratchet. Turn the engine counter clockwise until the number 1 piston arrives at TDC.





    Once you have #1 at TDC you can hang the timing chain and time the cams. It's a pretty easy process when following the manual. Both the exhaust and intake cams have a mark on them that lines up with a mark on the camshaft cap.

    Last edited by Green Hulk; 12-09-2009 at 01:07 PM.

  3. #3
    I wanna go fast perk_1405's Avatar
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    you are the man.

  4. #4
    SpeedJunky's Avatar
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    So with this new setup what will be your target RPM?

  5. #5
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by SpeedJunky View Post
    So with this new setup what will be your target RPM?

    I'm going to keep it at a conservative 8900 to 9000 RPM's.

    Another benefit to running higher RPM's is to help prevent overstuff at high speed. The more RPM's you turn the more water your pump is going to process thus reducing the chance of a stuff. This is starting to become a concern of mine with the speeds I'm seeing with this ski

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  7. #6
    SpeedJunky's Avatar
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    Nice work, amazing how far you have got that ski in such short time.

  8. #7
    cheatin' piston popper addicted's Avatar
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    that's cool. any idea why they only went with 4 valves instead of 5 like the last generation motor?

  9. #8
    Addicted Member 5001craig's Avatar
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    Awesome pics and write-up Jerry. Thanks!

  10. #9
    Site Admin Green Hulk's Avatar
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    Not sure why they only went with 4 valves.

  11. #10
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by 5001craig View Post
    Awesome pics and write-up Jerry. Thanks!

    Thanks Craig. Carey's a bit pissed i used her good towels but she'll get over it

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