I’m not sure when I began looking for a Silk. Only 138 were produced from 1975 through 1979. I had raced against one in New England in the late 70’s, but never saw another. I first saw the listing in some obscure corner of the internet, late at night, in the dead of winter, 2003. After 12 months of unpleasant haggling, I had made a deal at 40% above the original asking price. It’s easy to see why I don’t enjoy negotiating.
Of course, there is always a risk buying sight unseen, and an additional risk with a motor that has been dormant for decades. While the Silk was relatively easy to get running, a transmission defect immediately became apparent: it was jumping out of second gear. Maybe that was the reason it became dormant. Some research and patience soon had things sorted, and I began sifting through other minor problems.
George Silk took his passion for antique Scott motorcycles (as in Scott Flying Squirrel) and translated it into a simple yet effective motorcycle for the new era. Maybe George was ahead of his time, under-funded, or both, because his venture turned out to be commercially unviable. The motorcycle, however, was definitely viable, and Mr. Silk’s efforts to modernize a design from the 1930’s were, in fact, successful.
The 700cc 2 stroke twin is water cooled, with a prominent radiator in the conventional location. Unusually, there is no water pump, instead a large header tank above the radiator sets up a thermo-siphon effect that circulates coolant as needed. The automatic oil injection system uses a very robust aviation pump fed by a huge reservoir under the seat, good for nearly 1000 miles. The Silk evolved the Scott’s deflector top piston design, making it more compact, with advanced gas flow technology and port configuration, a 2 into 1 exhaust system, a single carb intake manifold design, and electronic ignition. The result is a power band a mile and a half wide. This big stroker pulls from under 2000 RPM to its 7000 RPM max, more like a big 4 stroke single.
The wide power band is no luxury, for the transmission, borrowed from a Velocette Venom, has only 4 speeds, and they‘re spaced wide apart. The gearing overall is rather tall, in the British fashion, so some slipping of the high lever effort clutch is required to get underway. With a perfect, gentlemanly, sporting British riding position: narrow sport bars with mildly rear-set footrests, one immediately feels at home on the machine, and the seat is plush.
At only 310 pounds, even the mere 45 horsepower that the mildly tuned, lightly stressed engine produces is adequate to maintain a respectable pace. The Spondon frame is an enlarged derivative of a 125cc road race frame, and features straight connections between the steering head and swing arm pivot, which is eccentrically mounted to allow for positively precise chain adjustment. Combine this with Girling shocks, Cerriani style forks, alloy rims, stainless steel spokes, Lockheed brakes and a gorgeous alloy 5 gallon fuel tank, and you have the quintessential British handling package.
The ride is….different, and pleasant above all. The long stroke 180 degree twin growls like an outboard on steroids, building power as the revs rise. Vibration is noticed as a buzz at higher RPM’s but the tall gearing insures that cruising speeds lie well below this range. The brakes are not overly sensitive, but cope easily with this lightweight. The steering and road-holding are remarkable, as only a 310 pound motorcycle can be. The skinny tires accentuate the airy feeling of lightness. Corners can be attacked and strafed with wild abandon, but do be careful. You wouldn’t want to wad up this much history.