Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126293
By John Waaser 00 ....-4 Consider You're a rider by England this. Your name is Glenn Vincent. machinist by vocation ' and a dirt avocation. You're a former New Sports Committee scrambles class champion. Your brother Charlie is a multi-medalist in ISOT competition as well as a former scrambles class champion, and you yourself have done well in ISOT qualifiers although you've never ridden the ISOT. Question: What do you ride for a woods bike? A high-powered gas· guzzling two stroke is out of the question even if they do handle better than most of the alternatives. Heavy, anachronistic, four-strokes are out, even the Trium ph 500 twin which wasn't bad in its day , because although old bikes don 't die, they do break a lot , no matter how well maintained. But wait a minute. Honda's fourstroke single isn't a bad engine. It starts readily; it's quiet; it doesn't leak oil. It 's smoother than many singles, and it pulls well all the way from an id le to about a zillion rpm. It 's the frame that's heavy and awk ward . And the lim ited suspension travel and poor compliance will ha ve you back on the pavement long before you've enjoyed the woods . Maybe the solution is the Honda engine in different rolling stock. But what rolling stock? Sure, you could weld lugs onto a Champion frame to hold the various bits and pieces you'd want that aren't necessary on a competition bike, but you'd still have a conventional motorcycle when you were finished . A good one, perhaps, but nothing truly distinctive. Wouldn't it be neater to use your machinist's talents and your imagination to come up with a better way? Let's see, now .. .the best for the air filter is up high . It should be in a I location protected from dust and mud but with unrestricted access to air . The electrics should be protected from water .- which also means high .. and covered but with air flow for cooling. The best place for the gas is down as low as possible. But as the gas gets closer to the carburetor, the fuel pressure drops, and fuel supply problems can crop up. That's why the old sidecar racers used weir -type fuel systems in which fuel was pumped from the main tank to a small tank which supplied the carbs. The excess drained back into the main tank. And there's nothing to say that the small tank can't be a sealed-off frame tube. They put oil in those things , don't they ? With its wet sump, the Honda doesn't need an oil supply. The gas tank could go in the normal air-filter location under the seat if the air filter were moved up . Pumping directly to the ca rb could be done if you switched to a snowmobile carb , bu t the needle valve on standard motorcycle carbs won't hack it. The weir principle applies however, and would allow the use of a standard motorcycle carb. That was the germ of the idea. Glenn had already done some work manufacturing special goodies for Husqvarnas, and he had produced a trick alloy swingarm which did not use any castings: in his opinion it was too difficult to join the dissimilar material.. cast to bar stock. And he had pulled in a good part-time living doing shock-angle mods to Elsinore frames for a couple of years when that was the hot setup. From all that , it was just a step up to a complete frame . The frame was designed to place th e shocks at an angle in a straight line Nothing fancy here. The pipe was fabricated from J.e. Whitney tubing (How trick is that71l and a Super Trapp silencer completes the exhaust system. 24 This trim-looking machine is Glenn Vincent's idea of what a woods bike should Suzuki forks and Fox Shox handle the suspension. Vincent designed and built One of the many unique and clever innovations found on the Vincent Hond is the front-mounted brake pedal.