Is my Crankshaft Spinning Correctly?
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  1. #1
    Junior Member JohnLouis24's Avatar
    Join Date
    Aug 2019

    Is my Crankshaft Spinning Correctly?

    Hello, new the this forum as well as bikes so forgive me for any arrogance. I have a 1973 Honda CB350 Twin and am currently in the process of rebuilding. Before attaching the lower and upper crankcase to each other, my crankshaft was able to spin without any hesitation, very smoothly. After closing the crankcase, the crankshaft takes much more effort to spin with the hand, immediately stopping once my hand stops. Not sure if this is normal or perhaps I have tightened the crankcase too tightly to where it is restricting how smoothly the crankshaft moves. Would greatly appreciate any input, thank you.

    (Any other advice you would like to offer regarding my first rebuild would be more than welcome as well, thanks again).

  2. #2
    Senior Member the-chauffeur's Avatar
    Join Date
    Nov 2009
    That's not right John. The crankshaft should spin relatively freely when it's mounted up and it should spin after you've let go of it. I'm not sure what's happened, and given that the bearings are roller (as opposed to shells) I can't quite work out what would be causing the friction. Equally, the bearings should mean your clearances are reasonably uniform all round, so it sounds more like something's out of alignment. First thing I would suspect is that the locating pin isn't sat right against the right hand bearing.

    But hang around here for a while and one of the others will jump in . . .
    CL77 (1966)
    CA77 (1966)
    SL350 K0 (1969)

    SL350 K2 (1971)
    CB450 K6 (1972)
    CB750 K2 (1972)

  3. #3
    Senior Member Bill H's Avatar
    Join Date
    Aug 2015
    Waverly Ohio USA
    I vote with the-chauffeur. If the cases went together then I would look for the side to side clearance.


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  5. #4
    Senior Member Gixxer-18's Avatar
    Join Date
    Nov 2014
    Weymouth UK
    Welcome to the forum, Sadly I think you'll have to open up the crankcase to inspect your bearings, as they have a location pin part number 90708286000 to stop the bearing outer from rotating in the crankcases. I suspect you have closed the crankcases without these dowel pins being in their correct holes...have you got a parts manual and FSM?
    2002 GSXR1000
    2005 R6
    2003 R6
    2003 Hyosung Comet 125
    1983 CB250RS
    1979 T140E Bonneville
    1976 CB360
    1975 T160 Trident
    1974 CL450
    1972 CB500/Four K1
    1972 CB350/Four K1
    1972 A100 Suzuki
    1957 T100

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