I have looked into it. The YBR isn't a fast bike to begin with but I'm confident that it could push on to 40+ mph (without a big bore kit), which is enough for my intentions. I've consulted a mechanic who has some contacts in other industries (welding, powder coating, and fibreglassing). He has suggested the big bore kit but he advised that I do a bit of research on reliability, as he generally refuses to modify bikes. I am well aware that reliability will suffer, but I was wondering about the capabilities of the crank shaft and the bottom end, rather than anything else. I am confident that the bike can pull the weight as standard, but more power and torque will be useful. The sidecar is going to fit to the down tubing in front of the frame, the rear section of the frame (just behind the engine), and the tail section. It will be designed to carry passengers, and it will be set up to handle properly, although I've been told that the majority of handling problems occur at 50mph+ so that shouldn't be too much of a problem. The sidecar isn't covered on an MOT, as it's classified as a modification, much like a tow bar on a car. However it will be well maintained. As I said before, the bike is only worth about £50 so I won't have lost a great deal if it doesn't work out.