Keen eyed readers will notice that I have posted here before on problems with my 1972 750 Commando crankshaft. The one which came with the bike was ruined beyond repair (QV). I then bought a second-hand crankshaft (in pieces) which I returned because a) the bolt holes didn't align and b) it was (0.018") bent.
Having given up on a decent SH crank I bought a brand new CNC machined steel crankshaft supplied unbalanced and sent it to my friendly engineer with conrods, pistons etc. for balancing,
The engineer has said that due to the holes in the flywheel the crank is already at 52% and will require weight added to get it to the 55% (dry) balance that he would consider a minimum. Additionally the drive and timing shafts are not concentric with the main bearing journals with a 0.010" (+/-0.005) runout.
I spoke to the supplier and he said the balance would be fine - "install it as it is" and that the runout would be unnoticable when installed.
My engineer thinks that installation in this state would be disastrous.
I'm between a rock and a hard place. What should I do? Install or return? and what alternatives exist?
Send it back.
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