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  1. #1
    is thinking. grantuk's Avatar
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    Ready to start???

    Hi,

    I'm re-fitting my head, it has the RR cam.

    - The cam and crank were locked,
    - cam chain tensioner is in,
    - cam gear bolts are in,
    - I can turn it over by hand,

    Here is a pic of the cam gear marks, this is as close as I could get them to parallel with the head surface.



    Also when turning the engine over by hand the valves pop-up on the springs every third of a turn, I assume this is normal due the spring tension?

    So is it ready to fire?

    Thanks


  2. #2
    Hydrotoys's Avatar
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    the valves pop-up on the springs every third of a turn

    What does this mean exactly?

  3. #3
    Moderator The Bandit's Avatar
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    It looks like it is retarded on the cam sprocket. Have you tried advancing the sprocket on the slotted holes? Hard to tell from the second picture. With the RR cam, you will need to advance it almost the whole way on the sprocket in order to achieve 135 compression. That would be the "sweet spot" for that cam. Maybe try advancing a tooth on the gear and then see how it sits.

  4. #4
    is thinking. grantuk's Avatar
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    Quote Originally Posted by Hydrotoys View Post
    What does this mean exactly?
    When turning the engine over by hand, the rockers compress the springs and then 'let go' as if the springs are popping back up as the cam rotates. Is this normal?

    Steve, I undertstand that I need the comp at 135psi, I just wanted to make sure it would run as is before I started checking compression etc. I will try advancing it a tooth, but I think I have tried this and the tensioner was too tight.

  5. #5
    Site Admin Green Hulk's Avatar
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    Grant, you have that Rotax Racing cam retarded. You need it advanced.

    1) Lock the cam with the cam locking tool
    2) make sure #3 is on TDC and no crank locking tool
    3) make sure sprocket bolts are semi loose
    4) rotate the driveshaft clock wise slightly until the right hash mark on the sprocket is slightly lower. This will put the sprocket bolts a little farther to the left in the slots. Don't go all the way but the bolts should be midway between all the way to the left in the slots and the halfway point in the slots.

    Now your cam is slightly advanced.
    5)tighten your sprocket bolts and remove cam locking tool.
    6)install and tighten up tensioner.

    You will know you have the cam timing right when you get 135 psi of compression.

  6. #6
    is thinking. grantuk's Avatar
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    Thanks, I will do it now.

    Can you just confirm the valve springs popping back up when turning over by hand is normal?

  7. #7
    Site Admin Green Hulk's Avatar
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    This is normal. The valves open and close as you rotate the crank.

  8. #8
    is thinking. grantuk's Avatar
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    Thanks for confirming, I have now advanced the cam adn it now looks like this...

    Slots...


    Good to go?

  9. #9
    is thinking. grantuk's Avatar
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    P.S. What are the torque specs for the cam gear bolts and is loctite requied?

  10. #10
    Moderator The Bandit's Avatar
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    Quote Originally Posted by grantuk View Post
    P.S. What are the torque specs for the cam gear bolts and is loctite requied?
    Now you are looking good. Jerry obviously does a much better job explaining it than I. He has gone through it with me, and God knows how many others.
    I am not sure of the torque specs. I did use red loctite on them though. I just tightened them by hand, pretty tight.

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