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  1. #1
    Member Ogoki's Avatar
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    CB450 Crankshaft Main Bearing Journal Wear

    I discovered what looks like some pretty heavy scoring (?) on one of the crank main bearing journals.

    How does this look to you guys? Like a write-off? Negligible (likely not)?

    I imagine it could be turned down, but then what would I do about bearings?

    Thanks for any info.
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    CB450

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  3. #2
    Supporting Member 450roo's Avatar
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    Re: CB450 Crankshaft Main Bearing Journal Wear

    Not an uncommon problem for the motors made in the early 70's. The hardening is pealing off the journal, I have had two motors where this happened, both had many miles on the clock. You can get the shaft turned down and get a hardened bush to fit over the journal. Not a DIY project you will have to talk to a motor engineering shop (not your local mechanic) about it.
    I would think about fitting a ball bearing as in the 500T but then I have the tools for such a job.
    Perhaps a used crank will be cheaper and easier?
    Good luck!
    CB450 K0, CB450 K2, CB450 K4, CB500T, and a 450/500T cafe racer/custom project now under construction.

  4. #3
    Supporting Member jensen's Avatar
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    Re: CB450 Crankshaft Main Bearing Journal Wear

    Hi,

    Indeed a common problem. You can repair it as suggested by 450roo or weld it up and grind it down (a specialised company can do that).

    Jensen
    assembly of Japanese motorcycles requires great peace of mind (Zen and the Art of Motorcycle Maintenance / Robert Pirsig)

  5. #4
    Member Ogoki's Avatar
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    Re: CB450 Crankshaft Main Bearing Journal Wear

    Thanks for the responses.

    In the event that a local machine shop can resurface that journal - and any others that might need it - what are the odds that my bearings are still usable?
    CB450

  6. #5
    Senior Member jays100's Avatar
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    Re: CB450 Crankshaft Main Bearing Journal Wear

    Another option is to grind then hard-chrome buildup then grind to size...just say'n!

    your photo looks to me that corrosion pitting is present too, that process may be the originator of the problems.

    check the rollers, if they have pitting too, is a very bad sign. surface roughness is another. I would suggest that with the roughness of the main journal that the rollers are bad too.

    It's possible to find a ball/roller bearing with a ID/OD that will bolt-in properly and without machining, then the oiling hole becomes the only issue but 45roo's suggestion is best. Can he do the work for you/has he done it before??
    J

  7. #6
    Member Ogoki's Avatar
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    Re: CB450 Crankshaft Main Bearing Journal Wear

    It sounds like 450roo could do it, although I imagine the postage and shipping time to and from Australia wouldn't make it the best course of action.

    Quote Originally Posted by 450roo
    Not an uncommon problem for the motors made in the early 70's.
    I think I might take my chances with a crank on ebay. Do the earlier, late-60's pieces tend to be any better?
    CB450

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