General Flywheel marks

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General Flywheel marks

OzNiki

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May 27, 2025
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Hi all,
Not a 500 classic but 1989 650 AC 126.
Does anyone know where the mark on the flywheel should be at TDC?

Asking due to pretty bad vibrations on acceleration.

Thanks! :)
 
There are no timing marks on the 126 flywheel. If a crank and flywheel have been balanced at some stage then it would be normal for the them to be marked for assembly purposes.
If you were unfortunate enough to have a Bis flywheel fitted then you would have some bad vibration.
 
There are no timing marks on the 126 flywheel. If a crank and flywheel have been balanced at some stage then it would be normal for the them to be marked for assembly purposes.
If you were unfortunate enough to have a Bis flywheel fitted then you would have some bad vibration.
So can the flywheel on the AC 126 be put back in any position?
 
So can the flywheel on the AC 126 be put back in any position?
Technically, yes---the flywheel CAN be put back in any position. Unlike the centrifugal oil-filter cover where the holes are NOT equidistant (so that the timing mark on the cover lines up with the timing mark on the pulley) the holes on the flywheel ARE equidistant. If as"Toshi" has mentioned, you have a BIS flywheel, (which is unlikely as they were only sold in very small numbers in Australia between 1989 and 1992 with the name "FSM Nicki") try another flywheel from a 'standard' 500. The 500 flywheel weighs 5.3 Kg whilst the 126 flywheel weighs 7.3 Kg, hence my suggestion that you try a standard 500 flywheel. Before fitting another flywheel, check all the components of your current fitted parts for correct fitment. If you wish to lighten a flywheel, first of all have the friction surface MINIMALLY skimmed (to ensure absolute flatness) and then have the unwanted material removed from the back of the flywheel---I would suggest that for a "road use only" car you do not go below 4-1/2 Kg in weight.
 
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