Well it looks quite well built to me, so, er, what's wrong with it? When I was about 14 years old I had a home built go-kart with a Royal Enfield 350 single cylinder engine and 4 speed gearbox, even with the little wheels it'd do 105 Mph, I know this because the PO/builder had a mate follow him along a country road at night and just before the kart left the road in a bend (it had terrible understeer at speed) and cleared a farm fence, the driver of the car saw 105 Mph on the speedo.
Of course I wanted "More Power" so I removed the 350 and fitted an RE 500 engine with an SU carb off a Mini, (on a home built manifold) and it went very well, although I never got to do a real "speed test" because none of my mates were old enough to hold a car license, ha ha!
Personally, I think that the mighty CB750 engine is more than capable of powering anything mechanical, and I'd be happy to own a CB750 powered wheelchair when I'm as old as some of you guys, ha ha! Cheers, "Mad Terry".
