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81 Shovelhead smoking a bit after warmup....

Discussion in 'Motorcycle Tech Talk' started by Charlie V., Sep 6, 2020.

  1. Charlie V.

    Charlie V. New Member

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    Did a search and came up empty, so posing the question to verify am on the right track. Have been doing some research, but can't hurt to make sure. :)
    Right now using synth 20w-50 oil, but going to be going to straight 50w. Problem is after up to temp, it will smoke, a bit more on the moving down rpms like on the downside of a throttle goose. Not on startup, but after warmup. Also on a short ride, daughter said it was smoking going down the road. Just nice and easy at about 40-45ish. Not real heavy, but the plugs, they do be black. As a dbl check, did a compression test both cold and hot, front is a solid 130 on both, and the rear has a Dif of 135 cold and 130 hot.
    It does have a S&S offset set of flywheels and a 440 cam if that may make any difference. And yes, had the throttle wide open both times :).
    If need any other info, let me know and thanks for any help/thoughts.
    Last edited: Sep 6, 2020
  2. hotroadking

    hotroadking Super Moderator Staff Member

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    does it do it when you ride around non WTFO?

    Does is smoke on start up?

    Have someone follow you while you ride a more reserved pace
    and see if it smokes
  3. Charlie V.

    Charlie V. New Member

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    No, not at startup, yes going down the road easily, and again, more so when reducing rpms.
    Last edited: Sep 6, 2020
  4. hotroadking

    hotroadking Super Moderator Staff Member

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    I see you mentioned the when in the op, went right past that

    Generally speaking

    If you see it at startup it's leaking valve seals,

    if it's going on while under normal power, possible rings.

    Only other thing would be if the oil breathers are dumping oil that
    is recirculating through the system but I doubt that would be it.
  5. Charlie V.

    Charlie V. New Member

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    Ok, was thinking more seals myself than rings due to the compression staying the same hot and cold. Have seen some write ups with the smoke after warmup leading towards vlv seals. If compression changed then more towards rings. Don't have a leak down tester or would check that as well :) It has been dumping if it sits more than about 10-12 days, would piss all over the floor like a happy puppy LOL. Have gone thru the ball and spring, replaced, tapped, lapped, changed the tappet spring. Has an S&S E on it but no oil breather lines or anything to the filter. Gas line in, that's it. Thanks for the input! Appreciate it.
  6. hotroadking

    hotroadking Super Moderator Staff Member

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    Spoke with a friend that has an 80 Shovel, and a motorcycle shop, here's his take

    I would say worn valve guides. Compression is good but could still have an oil ring problem. I would still lean towards valve guides and I would suggest switching to straight 60wt

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