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Wordman's Build (with questions, answers, and suggestions)

Discussion in 'The Garage' started by Wordman, Jul 21, 2019.

  1. Wordman

    Wordman XS650 Enthusiast

    Correct, the stock Triumph crank is a 360°. The Triumph doesn't have the central bearing though, so it also has a crank "whip" factor (the crank flexes in the middle like a jumprope. Going with a 76° crank, while a lot more expensive for a Triumph, does even more to quell the vibration.
  2. Raymond

    Raymond XS650 rider, fettler, setting out on a journey XS650.com Supporter Top Contributor

    Interesting - I've never seen a 76° crank for a Triumph. That flexing of the crank was always seen as putting a limit on the revs. Does the offset crank allow a higher rev limit?
    Jim likes this.
  3. Wordman

    Wordman XS650 Enthusiast

    Triumph always had a pretty high rev limit, they just felt like they might come apart (and sometimes did) when you approached it. In racing, the offset "billet" crank would allow you to stay at the limit longer and with fewer chances of turning the thing into a grenade, I would think. As I am going with a stroker crank and a much larger bore (840cc), I plan on staying with 9:1 (at most) compression and fairly "soft" cams so I won't have to rev the snot out of it to hit the highway now and again. The whole exercise is to build a strong and reliable Triumph.
  4. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    I see that the 76° crank doesn't have that insidious "sludge trap".
    Good filtration recommended...
    Wordman and gggGary like this.
  5. Wordman

    Wordman XS650 Enthusiast

    I've been running an external filter for years. The sludge trap was a good idea in the 30s and 40s, but with the advent of detergent oils, a good filter is a far better solution.
    Jim and Raymond like this.

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