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  1. #1
    urugol's Avatar
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    Fixing Burred Threads

    Hey guys,

    I want to get some opinions on the best way to deal with a burred thread in the cylinders, where the head torques onto. I have 2 out of 6 threads burred on the same cyl, right next to each other so I need to fix. I tried to clean it up, ran a fresh M8 tap, new bolt but it just spins when it gets to the end of the bolt. I'm thinking either helicoil or devcon plastic steel at this point. My worry would be rust, do the helicoil things typically come in SS? Also not sure if the steel in devcon is aluminium or other. I also thought of enlarging to M10 and re-tap but don't really want to go there as it could weaken the sides and I would need to drill a larger hole through the head as well. Would like to know what anyone else has done with success to deal with this type of problem


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Parts are cheap over here. I'd get a new cyl.....


    For you though, going up 1 bolt size shouldn't hurt too much.

  3. #3
    urugol's Avatar
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    I would if it was an old tired cyl, but it's perfectly honed and already in. Maybe M10 could be ok, it would be easy to re-tap the existing hole wouldn't even need to drill......

  4. #4
    Moderator beerdart's Avatar
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    Helicoil or timesert would be the way to go.

  5. #5

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    i like these the thread locking ones the best

    http://www.mcmaster.com/#threaded-inserts/=g6h7hz

  6. #6
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Quote Originally Posted by beerdart View Post
    Helicoil or timesert would be the way to go.
    Are any of them salt water resistant?

  7. #7
    Moderator beerdart's Avatar
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    Yes they make them in stainless but i dont see the need as the head bolt is sealed (For the most part)
    Quote Originally Posted by xlint89 View Post
    Are any of them salt water resistant?

  8. #8
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    What ski is this on?

    That salt gets into everything....

  9. #9
    urugol's Avatar
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    It's on my Yamaha. I wouldn't feel comfortable running anything less than SS to be honest. Not that I care for the bolt so much as the seal don't want any water washing a piston at 7,000 rpm. Another thought I had was running M8 but with a finer pitch but shorter so it forms a tighter thread it would be good for a couple of turns and easily get the torque I need. This would be a dodgy way but hey I still think it would work.

    Damn I wish we had a mcmasters over here!

  10. #10
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    We must be more helpful than the Yamaha guys........lol. Posting a question in the Polaris section for a Yamaha ski.......I would think you would be ok with any kind of insert. There should be no way water can get to that bolt.

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