I was going to lighten this using the mod found in the derestriction section however it looks different to the other types of flywheels seems to have some bearing type things on the outer edge
Those are what engage when the starter motor starts spining, turning the crank, they flick out with the cetrifugal force, should be another two of them where the bare spring is.
is it possible to fit this flywheel an starter to an engine that doesn't have electric start as standard an is ok to lighten the flywheel when using electric start