This is the gearbox kickstarter spring, as fitted to most Norton Upright and Laydown gearboxs (pre-AMC) from 1930's to late 1950's. Original kickstarter springs commonly wear on Norton gearbox's - often identifiable by the kickstarter moving backwards by its own accord on takeoff from standstill.
As with the Gearbox Selector Fork Return Spring Item 0384), this kickstarter spring is commonly worn on Norton gearbox's - often identifiable by the kickstarter moving backwards by its own accord on takeoff from standstill, or just being floppy and ineffective.
As with the Selector Fork Return Spring, a good quality original was used as a template and manufactured by our top quality UK spring manufacturer
Fitting Instructions (See also second picture)
Fitting it is a relatively simple exercise, but can be fiddly - and as with all spring fitting eye protection should be used:
Remove the pressed steel end cover on the kickstart shaft and prise out the old spring from where it locates vertically in the kickstart shaft - always wear safety glasses when doing this, although it should not fly off (in case it should break). Then slide off the old spring - but before removing you may want make a note where the old spring located into one of the 4 notch's placed radially around the steel sleeve that the kickstart shaft fits into.
To fit the new spring - you first need to ensure the kickstart shaft is turned as far clockwise as it can go - this signifies the kickstarter being at the top of its swing. Then fit the new spring over the shaft, I use a pair of pliers to lever the inward facing tang over the end of the shaft, and then gently move it back (a bit fiddly as the tang will be pressed hard against the kickstarter knurl), until the tang enters the hole on the kicstarter shaft.
Then, the idea is to try and rotate the spring as far clockwise as you can achieve, until the spring is in as much tension as possible, and the parrallel tang engages with one of the four slots in the kickstarter shaft sleeve (which is shrunk fit into the outer gearbox cover). Obviously, this is not easy - and if it does turn out to be easy . . . you need to check to see if you think you could have gone another quarter turn. The more tension that can be applied to the spring, the firmer the return of the kickstarter will be.
. . . And if you are sweating and swearing when you are doing this - don't despair, that is normal! Once fitted, if correct, the kickstarter should return to the vertical easily on its own accord after starting the bike, and not flop around in use.
And again always wear eyeglasses when doing this - as you should when doing anything with springs.