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  1. #1
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    Default Silly Balancing Questions..

    I've developed a fondness for Mr. Tatro Machine's YouTube channel. (HERE, if you are interested)

    In some of his videos he does flywheel balancing, and the way he does it is one half at a time with a bob weight. This seems to be the standard way.

    Is there some reason I can't just put both half's together, attach the weight around the crank pin and do it all in one move?

    I know just enough to be dangerous, so any information you have will be useful.


  2. #2

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    If the flywheel assembly is being dynamically balanced, that is done as you describe, and the machine will indicate which flywheel (in this case) needs material removed (or added) and where.

    When static balancing, you cannot determine which flywheel needs weight added or removed. Therefore, to approximate a decent balancing job, each flywheel is treated individually, with half the bobweight. The additional benefit is that you don't have to assemble and true the flywheels in order to balance them.

    Jim

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    Quote Originally Posted by JBinNC View Post
    If the flywheel assembly is being dynamically balanced, that is done as you describe, and the machine will indicate which flywheel (in this case) needs material removed (or added) and where.

    When static balancing, you cannot determine which flywheel needs weight added or removed. Therefore, to approximate a decent balancing job, each flywheel is treated individually, with half the bobweight. The additional benefit is that you don't have to assemble and true the flywheels in order to balance them.

    Jim
    *Thumbs up!*



    Is there an inexpensive spindle I can buy to mount these while I do it?

    I have a ShopSmith style lathe and mill, but I'm not very good with it. Worst case, I could probably make something.

    It is difficult here because there aren't a great number of Shovels. The indy dealer near me doesn't even do machine work anymore. He sells newer bikes in his showroom and fixes lawnmowers.

    Just not a lot of interest in this market.

  4. #4

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    I balance almost every bottom end that comes into my shop. I made my own knife edge fixture and bob weight kit, but bought the shafts individually from S&S as I needed them. (I have the full set now.) It's more important than ever, in my opinion, to balance older motors, because the replacement piston weights have changed so much.

    Jim

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    Had a customer insist on shipping a set of assembled flywheels out to some fancy computer controlled "dynamic" balancer...
    Pistons and all.
    They even trued and welded the crank (twin cam)
    Worst vibrating mill ever assembled.
    Needless to say, no one was happy.

    I use the Bob weight method and only tweek the percentage if race bike.

    https://youtu.be/x0NK_br-NyI

  6. #6

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    I've been tweaking the percentages for thirty years.

    Jim

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    This has been very helpful.. Thank you.

    I was looking for a wheel balancing arbor and ended up finding a bearing mounted balancing assembly designed for motorcycle wheels on amazon for $49. It has adjustable cones and looks like it will work just fine.

    Find out next week.

    Thanks again!


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    Quote Originally Posted by Sky View Post
    Wonder if that carpenter level is close to being as accurate as a machinist level ..??



    Or if it even matters that much ... ??
    Last edited by Dragstews; 08-25-2019 at 11:54 AM.

  9. #9

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    I had the same thought, but considering the balance method he is using (old Indian method), does it really matter?

    Jim

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    Tatro breaks out a cool, digital level, from time to time..

    In theory, they should be very accurate. Amazon has some that are affordable.

    I was going to try one of those.

  11. #11

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    Digital does not equal accurate. The machinist's level Drag pictured above is graduated in .005" in 10", and is a very good tool to have around the machine shop. I've had good use out of mine. I've got another that is ten times as sensitive, .0005" in 10", but it is overkill for general work.

    Jim

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    Quote Originally Posted by confab View Post
    Tatro breaks out a cool, digital level, from time to time..

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  14. #14
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    Holy hell.. that one has 92% of users giving it 4 or 5 stars.

    You can't get 92% of people to agree on the color of the sky.

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    If you have a machine shop, even a small hobby shop at home, the Starrett 12" machinist's level is a good tool to have for leveling the machines. And if as in the video above, you are using knife edges to balance flywheels, the knife edges must be level.

    If you are going to use a balance stand with four bearings, having it level is not so important. You may want to level it side to side so the work stays centered, but a torpedo level or some such will suffice for that.

    Jim

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    Looks like you practically have to be a machinist to own a Harley and work on it yourself?

    Had no idea they were this involved.

    Still happy with it. Still a great project.

    But I really never expected this level of intricacy with the Harley Davidson.

    Growing up, I knew a thousand of these guys. And the Harley guys around here fixed them in their garages, without much in the way of special tools.. and no machine tools whatsoever.. and I just kind of got the idea that they weren't very involved?

    Guess it is like anything else - Doing it right is much more complicated than doing it wrong.

    Been a real learning experience so far..

    Thanks to everyone.

  17. #17

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    The newest shovelhead is now 35 years old, and so these old machines need more intricate repair than they did when they were new(er). If you were working on a five year old twin cam, you would probably not need too much machining.

    For the hobbyist, you have two choices, tool up to do the repair work you are comfortable with, or willing to learn, or farm some of the specialty work out to specialists. With the innertube and the resulting connectivity, you can get most anything done, if you don't mind the postage.

    Jim

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    Looks like you practically have to be a machinist to own a Harley and work on it yourself?
    Only for crankshaft work, cylinder boring and similar work which has always needed specialty equipment no matter the brand and HDs don't need much. Think about it compared to any other bike or auto engine.

    Plain bearing engines require crankshaft grinding if worn beyond limits. You can't do that without machine tools. You can manually replace a pre-Twin Cam Harley crank pin.

  19. #19

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    Quote Originally Posted by JBinNC View Post
    I've been tweaking the percentages for thirty years.

    Jim
    What percentages do you go for on a stock panhead ?

  20. #20
    SamHain
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    Quote Originally Posted by farmall View Post
    Only for crankshaft work, cylinder boring and similar work which has always needed specialty equipment no matter the brand and HDs don't need much. Think about it compared to any other bike or auto engine.

    Plain bearing engines require crankshaft grinding if worn beyond limits. You can't do that without machine tools. You can manually replace a pre-Twin Cam Harley crank pin.
    With a big enough press you don’t have to stop at twin cam.

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