Heavy Flywheel vs Light Flywheel Reliablity on CB/Prewar

[The Bradford man]

Heavy Flywheel vs Light Flywheel Reliablity on CB/Prewar

My Father noticed that almost every CB Bradford/Prewar motor that had a broken crankshaft, was almost always fitted with a lightened flywheel.
Has any one else noticed the same thing.
Any ideas why the lightened flywheel would cause higher failure rate compared to the heavier one?

Thanks

[Keith Clements]

A heavy flywheel puts less strain on the crank. It is a bit like the energy recovery system used in an F1 car. When a load is put on it through the gearbox the energy stored in the flywheel delivers what it can giving the engine time to add some more.

[The Bradford man]

Thanks Keith.