Bent (output) shaft sindrome

Discussion in 'Motorbike Technical Discussion' started by ade, Jul 31, 2006.

  1. ade

    ade Guest

    Hi there.

    I was involved recently in changing sprocket and chain of my Honda
    hornet 600. The chain i had on was the original from Honda and lasted a
    honerable 10966 miles. As I'm new to maintenance jobs and repair jobs i
    have a question for the expert audience of this group.

    I removed chain and sprockets from the motorbike and installed the new
    ones. Once I've aligned the rear wheel i checked for tight spots and
    check the tension in different parts of the wheel. Once i was satisfied
    with the result i wanted to see if everything looked fine. With the
    bike on the rear wheel stand i started the engine and putted it in 1st
    gear. I sat down behind the rear wheel looking the rear sprocket. The
    rear sprocket had no lateral oscillations and i was perfectly aligned.
    Looking at the chain getting feed to the drive sprocket i noticed the
    chain oscillating slightly from left to right as the chain engaged in
    the drive sprocket (this is only 3-4 millimetres but still very
    evident). When i inspected the old drive sprocket, which was installed
    on the output shaft, i noticed that it was not rotating perfectly, but
    it had some anomalies, with slight oscillations.... I associated this
    with the fact that the sprocket were worn.

    Now i installed a new drive sprocket and there is still oscillations.
    Is this normal or the bike could have a bent output shaft? There is no
    oil leak on the output shaft, but will it quickly wear the chain? Could
    tell me if the drive sprocket should be aligned straight without
    oscillations or is it normal to have some oscillations.

    Your help is very appreciated.
    ade, Jul 31, 2006
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  2. ade

    FB Guest

    Are the insides of the link plates on the old chain worn to where they
    are polished and shiny bright? That indicates sprocket misalignment.

    I noticed the chain walking from side to side on my GSXR-750 and took
    steps to shim the countershaft sprocket and the rear sprocket, but the
    chain *still* walks from side to side.

    Why? It seems that the original equipment chain had thicker side plates
    and the aftermarket chain has thinner sideplates. So the chain walks
    from side to side as the rear wheel turns.

    It's very difficult to bend a transmission countershaft, but I suppose
    you could manage it if you had a hydraulic press and applied tons of
    force to the shaft.

    You could easily determine whether the shaft is bent by watching the
    end of it as it rotates. There is probably a pilot hole on the end of
    the shaft that you can see. It's for turning the shaft in a lathe.

    If you mark the exact center of the with a dab white paint and run the
    engine and the
    white mark appears to go around in a circle, the shaft is bent.
    FB, Jul 31, 2006
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  3. ade

    ade Guest

    You are right, i've replaced the original sproket with aftermarket one.
    The drive sproket had ticker side plates, i remember that. i'll buy a
    original drive sproket and check if the oscilations are reduced.

    Thanks for your help
    ade, Aug 1, 2006
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