Talking to Bob the other day we discussed the means to drive the sleeve. As the sleeve drive shaft needs to rotate in the same direction as the main crankshaft, chain drive seems to be the easiest method.

Bob had dug out a triumph boneville manual from his library and showed me the primary drive arrangement. The drive ratio is perfect at 2:1, and the chain tensioning method would suit us too. The sprockets are physically too large, so we’d go down to 22:44 teeth from the original 29:58.

Bob showed me some calculations he’d done which are quite impressive. The distance between the shafts on the Boneville isn’t stated, but knowing the chain length and sprocket sizes he was able to calculate this. Transposing this to our sprocket sizes means that the chain tensioner will still fit. That does make life easier.