quote auldscott:
If it were my motor I would either use a smaller diameter pipe or a single washer that was at least twice as thick as the one in the pic. Not having ever done such a mod, I’d want to be sure that deflection of the washer would not result in the flywheel working loose, which would damage the crankshaft and/or the flywheel.
Agreed. Then if you keep an eye on it to make sure torque isn’t being lost, you should be OK.