This is something I've been thinking about doing for a number of years. I've built motorcycle and car engine trikes but got into mopeds as they take up a lot less space so you can have more of them. I'd bought a project bike that had the rear of the frame cut off so thought it would make a good basis for a replica of the factory built trikes. The axles options were either a ride on mower one with a peerless diff like the Prior conversions, a solid axle with free wheeling hubs like the factory ones or just drive the one wheel which is the option I went with. Quad axles are okay on loose or wet surfaces but on tarmac or concrete it's impossible to turn. I know this from putting an LT50 axle on a tomos just to prove to myself it was a bad idea. I use to have a BSA ariel 3 so the 1 driven wheel didn't bother me.The width of the rear axle is much wider for stability but is just under 460mm which in the UK classes it as having 1 wheel. This means it can be MOT'd as a class 1 and not class 3. Engine will be standard A3 with a hi compression head which I skim myself on the lathe. Gearing will be 26t front and either 22T or 24T rear depending on which gives the best balance of road speed and load pulling. It would be nice to fit a geared AT50 engine but I've got to make do with what I've got for now.
