What an awesome little bike! I can't help but think of a few improvements - I'll bet it stops well, what with the weight, but I still love the look of an over-sized drum-brake. The main reason to re-build some wheels - maybe there are some BMX aluminum rims out there for cheap. Most of 'em are 36 hole, matching with most drum hubs. The rolling inertia would be cut in half, going from a chromed-steel rim to an aluminum one, and on top of that go down to a tire and tube with a quarter of the mass. The thinner lighter bicycle spokes and softer tires might even help with suspension. Or, the right diameter of wire-spoked drums might just bolt straight up to some kind of Honda Monkey style rims, for a fat 8"-10"-12" scooter tire. Something like a CB350 drum would probably just tuck right into rims like that. And there are plenty of Aluminum rims made for those bikes these days. I still like the BMX idea though, rather than fatter tires I think weight is the biggest consideration. And me, I'm so pre-occupied with wheels and wire-spoked wheels it's like some kind of fettish. Damn I just love the shaft drive on this thing. Anyway yeah, I'm thinking you could save a heck of a lot of weight on those wheels with some alloy rims, and at the weight and attainable speed I wonder whether bicycle tires would be reasonable. Probably not something you'd get past a safety inspection though. Ha ha. You don't NEED to do all that shit though, as your creation is beautiful enough as it is. - That's the thing you've pulled off here, is making one of these putt-putts BEAUTIFUL. Who'd have thunk it? An amazing transformation. This is going up on my screen saver along with all of the other great café bikes of the world. The QT sure is an interesting design, with the engine moving integral with the swingarm, much like a modern scooter's CVT tranny - this must simplify the shaft-drive a whole lot - no shaft jacking I'd bet. They could have done a typical CVT style, it was around at the time - but this design probably saves a massive amount of weight over a typical lay-out. As such, I see it as imperative to build the rest of the bike as an ultra-light. Obviously, you don't wanna dump a huge amount of cash into this, but there's potential to use one of these things for a really competitive racer. Even an Electric, a motor in-line with that shaft would probably cool a lot easier, with the air-flow. Or a 50cc fossil class racer, obviously. Gotta be another barrel and head that could fit to that motor too.... Back to the chassis I think some kind of brazed chromoly or alloy would cut the weight down big time. Or even carbon-fiber. I mean, what with the way it all hooks together there's so little attachment points to factor in, it could be so simple. That main motor mount could utilize the crank of a standard bicycle frame with a polyurethane bushing to fill out the difference, so maybe there's a crashed/cracked carbon-fiber bicycle that would donate what's needed, it wouldn't need any construction done. I also think the telescopic fork is a lot of weight on something this size - there are those small springer forks made for banana seat bikes, maybe that would weigh a lot less - with some friction dampers like an old Girder fork. Then again, the fork sure lends an appearance of a "proper" motorcycle to the whole thing, as does the tank and seat. Your solid welded frame has gotta reassure the rider that the thing's not gonna fold in half and eat his nuts off. But yeah, what I see in this bike is an awesome race scooter that could blow away all of the modern stuff, not by making more power (though MAYBE that can be dealt with too) but by stripping away all extraneous weight. Maybe some kind of stream-lining on it, or the rider laying flat out superman style wearing a speedo just like Rollie Free! A small fairing would go a long way on this thing, the thing's so small that really the only thing to streamline would be the rider's ass. Compare that to the typical 50cc scooter. They've probably got rules about having to use the original frame, but heck you don't have to put the seat in the normal position. Maybe one of those reclining bicycle set-ups would mate to it. That's the one truly ridiculous thing about those streamlined bicycle racers ... well the most ridiculous thing - is that they don't simply stick a 50cc engine in there. I'm not saying this is what you should do with YOUR bike of course, I'm just saying, the GT50 is such a simple lay-out that you could put it on practically anything. I wonder if that shaft-drive hub would mate to a skate-board wheel, or one of those powered side-walk "scooters" -it's a huge power up-grade for one of those little things. Know what I mean? It's just such a compact complete engine and drive-train it's ridiculous. I guess the shaft-drive robs a lot of power, which is what I've always criticized about the typical CVT drive scooters out there these days. Gave my kid $ for a scooter for her 14th, didn't wanna cramp her style and TELL her what to get - she bought a Jazz/Metro. It really chaps my ass that we didn't fix up my old Passport instead, 'cause there's so much you can DO with them. The really trick thing would be to figure out which of the clone engines would fit to a KZ250/KZ305CSR belt-drive pulley, and save that much power over the chain-drive - then you've got something as clean and tidy as the shaft but without all of the power losses. That's what I'm trying to figure out now - which is to say, I've got ENOUGH bike projects. But this build is inspiring. Even on top of all the other shit I'm already doing: the KZ café for the kid and my DOHC Honda, another DOHC Honda in the near future for the kid, and the old C70 Passport and spare C70 frame which is begging to become a duplicate "his and hers" matched pair of duelling pistols - STILL, even with all that on the books I'd still love to dig up an old QT50 and play around with all the images swimming around in my head.
-S.