Bob called round the other day for a talk about engines, to see if I’d digested all the info he left over Christmas. I had as it happens, but understanding how things work isn’t my issue. I was working up to asking for some help with the drawing board. I haven’t used one since TD in school, some 30 years ago!! I’d have less of a challenge doing a design in CAD, but the software can be expensive.

We ended up around Bob’s drawing board to look into a few design issues. Bob’s sleeve valve drawings were up and we talked about which aspects we could incorporate, and those we’d need to change. We also had the Bristol drawings to hand which was very useful. It was a great way to spend the afternoon, he’s a good guy to bounce ideas off and we worked well together.

Items for consideration were briefly :

Driving the sleeve will probably be by chain, as the sleeve drive runs in the same direction as the crankshaft on the Hercules. Using a geared drive as per Bob’s engine would reverse the direction, which won’t do.

The gas flow through the Hercules is from rear to front, along the axis of the crankshaft. When fitted to a bike the gas flow will be from side to side, as the crank will have been turned through 90 degrees. This is unfortunate as it would look nice being more conventional, but designing in a bevel to swing the sleeve drive through 90 degrees would make it very complex.

It all looks doable, as long as I can source the parts! Just before I left, Bob asks me "Would you mind if I start drawing it up full size?". Would I?! Of course! I’m honored to have him fully on board for the project!!