Balacned Lightweight Norton Crankshaft

Typical lightweight flywheel offset Norton crankshaft after balancing. This image shows optional sludge traps plugs which are recommended for high-mileage machines. An in-line oil filter is recommended for all cranks when sludge trap plugs are installed. Norton light-weight crankshafts will be dis-continued on September 1, 2016.

Note size of counterweight and amount of steel around big-end journal. In combination with the large oil cavity in the flywheel this means both the total crankshaft weight, and the interial weight, are significantly less then a stock crank. Total weight is about 4.5 to 5 pounds (2.3kg) lighter then a stock crank depending on connecting rods and piston weight used. This crankshaft was balanced for 325gram pistons E&V forged pistons and R&R alloy connecting rods. Hepolite, and similar style pistons, weigh about 425 grams. The combination of R&R connecting rods and E&V pistons means the counterweights at a 50% balance factor are almost 100 grams lighter.

Lightweight Norton crankshaft engines are sensitive to how they are mounted. A solidly mounted engine may have a narrow RPM range in which the crank is smoothest. The typical balance factor of 50% may be changed a bit for these engines. These offset cranks are still a lot smoother then a stock Norton crankshaft that is solidly mounted. An Isolastic-mounted engine that uses an offset lightweight crankshaft is perfect at the 50% balance factor at any RPM. Racing cranks may be balanced at 40 to 45% depending on the RPM range that the rider expects the crank to be smoothest.

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