kick start spring replacement

[BSA_54A10]

Angus
put the old battery on charge (the correct way around) it could well recover, with a bit of luck it maybe has reversed polarity and could be reversed back, not guaranteed but worth a shot

The plates are different alloys and depending upon how long it was run back wards it could very well be cactus.
Most solid state regulators are not reverse polarity safe so yes it very well could be fried,

[Gonemad]

Bingo, I have before me a broken kick starter return spring and will order a new one right away.  I do have to order a new gasket too because parts of it remained faithfull to the gearbox while other parts maintained their loyalty to the cover.  Interestingly I didn't have to resort to the razor blade idea.  The cover came off after a gentle wiggling between the kick start lever and the gear lever.
For me the work was a trip down memory lane as I uncovered old spanners that have lain in wait for, errr, fifty years.  There in my old tools tool box were the old King Dick pipe spanners one of which was invaluable for the top cover nuts.  Also, I found my old BSA tappet spanner last used on my Shooting Star in about 1958.
Although everything inside the cover, that is visible, looks in remarkably good condition I was a bit alarmed at the colour of the oil that came out.  It seems to have a golden metalic appearance.  Still, as they say...'If it 'aint broke....' I will fill with new oil of course, to the correct spec.  I have read that some people use engine oil while others use ATF.  The oil that came out has that lovely smell of high pressure gear oil.

Regarding the battery, the second new battery was only on the wrong way around for very short time. It seems to have recovered from having lost its charge, faster than lightning, so I will see how it goes.  The first new one was disposed of in a responsible way and is now contributing to the polution of our planet in a land fill somewhere I suppose.

I have no idea of how to test a solid state constant voltage regulator so, for only £30, it is better for me to have a new one and then I can be certain that is OK at least.

Thank you for all your help so far Gents. 

[Gonemad]

Kick start spring in place with gearbox cover also in place.  So, that's part one of the issues with the bike over.  Thanks to those that offered good advice, much appreciated.

I used a clear silicon gasket goo and, following the advice on the packet, smeared a little oil on the gearbox cover which will hopefully allow the cover to come off again one day.  The oil came from the oil tank and, much to my surprise for a bike that has been restored and unused, came out a filthy black.  Next job then, change the engine oil, fill the gearbox and drain a refill the primary chain case.

After that..... see post on electrical things.

[jjbsa]

A long shot about your magneto.....  It is possible to assemble the mag end cap wrongly, so that the carbon brush in the middle is not insulated from the body, as it should be.  If so, no amount of kicking will make the mag spark.  Might be worth a check, as you say the mag was thought to have been recdently overhauled.