Dear Dripfeed. Back in about 1973 I bought a 1928 built TT Replica that has been unused since 1953 when it broke a crank. It had been owned by a very able engineer called Marriott. He had made up a cradle to replace the mag platform with two seating bars cut out to conform to the diameter of a Lucas dynamo. The dynamo was fitted with a small vee belt pulley which was (from memory) size A. A vee belt pulley was fitted to the outside of the clutch drum. On the RH door was a small contact breaker to time the sparks. There were, of course, the regulator coil and battery as usual. He told me that it was a totally reliable system.
I mentally doffed my cap to an ingenious engineer, but when I made my own electronic ignition, I also drove it from the clutch drum, but via a toothed flat belt, as I needed to maintain timing accuracy. Many owners have made their own variations on this theme, often because the short life of mag chains. In this respect there is an option to fit a chain of very significantly greater durability. In this case use a 3/16 wide chain as is used on 125 racers for a rear chain. The extra width will not have any adverse effect. I would suggest an IWIS Chain P_83V x 68 pitches including spring link from The Chain Man
Andy Forsdick
11 Gloucester Way
Bewdley
Worcs. DY12 1QF
tel 01299 403688
Mob 07860 577919
andy@the-chain-man.co.uk
