The gearbox sprocket

Provided by Godfrey Knight

Some time ago I had trouble with a rattling chain. I tried adjusting the chain tighter but that didn't work and the chain ended up too tight.

Looking into the problem more deeply I found that the chain was rubbing on the kick start return spring and beginning to abrade it; a situation that couldn't be allowed to continue. The problem lay with the spring which is a two layer helical spring used in torsion. The free end of the spring had extended itself into the area used by the chain and needed to be ' pushed back' into its own area.

The working solution was to make a large diameter washer, the o/d of the spring and fit it on the kick start shaft to limit the extent to which the spring could extend into the chain's territory. Below are the notes I made after the job was done:-

•  Fitted washer on kickstart shaft to prevent the starter return spring being abraded by the chain.
• Washer to be fitted 55mm o/d  x 22mm i/d  x  3mm thick. Deep chamfer on chain side of o/d.

Method

• Remove kick-start/quadrant unit. (not easy.)
• Remove existing small dia. washer.
• Replace with new large dia. washer; chamfer towards the chain.
• Replace kickstart/quadrant unit

This solved the rattling chain problem.