During the fitting of a starter to my GF I had decided to retain the 6v system and charge the 12v battery as required. That would necessitate putting the 6v battery in the toolbox. Not impossible, but would ideally require a smaller battery. After some thought, I decided it would be easier to change the regulator and run the existing dynamo at 12v. And, in order to help things along I opted to change the dynamo sprocket to 11 teeth and therefore ordered an 11t sprocket on April 4th. After a couple of weeks I suspected it would never arrive, and so I ordered another (different seller) on 22nd. That hasn't arrived yet either. What's up with Royal Mail these days?
Anyway, I had hoped to get the bike finished off over Easter, and here we are - May 6th - and still nothing. So today, not wanting to order a 3rd and wait another two weeks, I decided to make one. I don't have sprocket cutters (one needs a set to cover various teeth sizes for every pitch of chain) and so I drilled a disc and eased the tooth profile with two passes of different size endmills. Over to the Boxford to bore the taper, a quick touch up with a file and flame harden and job done - exactly two hours. Should have done that in the first place.
Spent half as long again fitting the dynamo and chain. Another wonderful bit of BSA design - got to feed the chain around the drive sprocket whilst turning the engine over because it won't pass underneath. And the run-out of the drive sprocket is appalling. When you study the many shortcomings / design failings of these engines it's a wonder they run at all.
