Just in case you had any lingering doubts, that is definitely a W2.
It appears you have got the carb and exhaust transposed. Not sure if it would run this way round? You would have to turn the piston round. I cant remember at the moment which is the right way for the inlet, step or slope? No doubt Roland or Steve will be along with the right answers. A lot depends on the port positions and the position of the transfer port. Looks to me like thats on the other side. That lovely adaptor could still be used to link into the silencer if it has to be the other way round!
Shame about the cap screws, surely studs and nuts would fit?
Hi, Mark, Yes I am convinced. In fact, during earlier discussions, we were fairly sure it was a W2 but an accepted expert said it was a P3. Yup, I'll have to turn the piston round but that's no big deal.
The adapter came with it, which is why I set it up that way.
Why shame? I love them and no there's no way of using nuts unles I do a load of machining on the cylinder and flange.
Hope you like the engine,