All Norton crankshafts are machined, welded, ground, balanced and nitride heat treated for extra strength and wear resistance. A new flywheel replaces the original flywheel. Crankshaft Customers must supply weight of one piston with rings, wrist pin, cir-clips and identify the connecting rods they plan to use (stock or other). The customer is responsible for making sure that each piston weighs the same amount. The drive side journal is offset behind the timing side journal, in the direction of crank rotation, by 90°.
All cranks are lighter then stock so they have less inertial weight for faster acceleration. Norton Atlas and Commando crankshafts are balanced to 50% unless another balance factor is specified by customer. The higher the RPM range where a desired smoothness is required the lower the balance factor number. A racing engine may use a balance factor of 45% for best smoothness above 5000 rpm while a 40% balance factor is used for best smoothness above 6000 rpm.