Balance Factor

Does anyone knows what the balance factor of singles was when the

engines left the factory?

I have a 1956 Mod. 19  with a modified big end and the actual balance factor is 43%

I am going to re-balance the crank but I don´t want to drill too much so I can´t go back to

a original big end when that time comes

Regards

Göran Svensson

Hi.

According to P L Garrat's book Norton Motorcycles (he worked at Norton's) the balance factor for the Mod. 19 is 50%. My ES2 runs at this balance factor and is pretty smooth.

Cheers.

Ian.