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Thread: Panhead cylinder downgrade

  1. #1
    Join Date
    Nov 2010
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    Default Panhead cylinder downgrade

    I'm getting ready to restore a pair of heads that have been molested. Should I use a left handed drill bit to pull the plug out or use a screw extractor and do it slowly by hand?

    CIMG1879.jpg

    Thanks, Craig

  2. #2
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    Quote Originally Posted by 41craig View Post
    I'm getting ready to restore a pair of heads that have been molested. Should I use a left handed drill bit to pull the plug out or use a screw extractor and do it slowly by hand?

    CIMG1879.jpg

    Thanks, Craig
    Beware extractors expand things, Craig!

    For a left-hand bit to pull that large of stud sounds like abuse of tooling, (if not your tooling budget), unless you are real, real lucky.

    Any chance you could weld a smaller bolt to it?

    Often that heat is enough to loosen things, and the hex makes it easy to wrench out,.. If you are lucky, of course.

    ....Cotten
    Last edited by T. Cotten; 10-15-2020 at 04:33 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #3
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    I've had pretty good luck welding a flat washer to the broken bolt then welding a nut to the washer

  4. #4
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    First you need to determine if it is a cut off bolt or a cast iron plug.
    Robbie Knight Amca #2736

  5. #5
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    I would consider drilling a 3/16 hole clean through it to help relieve some internal pressure first. Then fill it up with Kroil or ATF and acetone for a few days. Then turn down a 5/16 bolt to fit the hole, bevel it right at the shoulder and weld it to the broken bolt. You could try a easy out first but I would not get rough with it. It all depends on weather it twisted off from over tightening or trying to remove it when it was tight in the threads. If it broke from over tightening it should be easy to remove.
    Jim D

  6. #6
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    Quote Originally Posted by jim d View Post
    I would consider drilling a 3/16 hole clean through it to help relieve some internal pressure first. Then fill it up with Kroil or ATF and acetone for a few days. Then turn down a 5/16 bolt to fit the hole, bevel it right at the shoulder and weld it to the broken bolt. You could try a easy out first but I would not get rough with it. It all depends on weather it twisted off from over tightening or trying to remove it when it was tight in the threads. If it broke from over tightening it should be easy to remove.
    It did not "break", it was a plug for the original hole....
    Robbie Knight Amca #2736

  7. #7
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    Thanks to all for the advice ! Good point Cotten on the expansion theory.
    Robbie; It is a cut off head bolt. It looks like a trip to my welder to attach a couple of bolts.

    I never got the practice of using Pan Cylinders in the first place. The bottom flange would hang over the edges. Also, when building choppers, the idea was to clean up the bike and motor lines. Not add ugliness to it. This was some of the Poor Advice that used to be in the old Choppers Magazine and others. Most of the early Easyriders Tech Tips were pitiful advice.

    Thanks again, Craig

  8. #8
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    There was a time before the 'aftermarket' when Knuck cylinders were scarce, and Pan cylinders were plentiful & cheap. we were not so concerned with originality, just wanted to keep riding.

  9. #9
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    drinner-okc; We didn't have a Knuckle cylinder shortage in the St. Louis area, but I do remember the Chop Mags telling Knucklehead riders about how brittle and fragile the OEM cylinders were. Although they weren't.
    Craig

  10. #10
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    While I would not consider OEM knucklehead cylinders fragile they surely do not have the reserve of strength that a panhead cylinder has.

    Jerry

    Quote Originally Posted by 41craig View Post
    drinner-okc; We didn't have a Knuckle cylinder shortage in the St. Louis area, but I do remember the Chop Mags telling Knucklehead riders about how brittle and fragile the OEM cylinders were. Although they weren't.
    Craig

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