Introduced in 1967 and displacing 745cc’s with pre-unit construction that was rather unimpressive in specification, Norton’s Commando was a development of the Atlas and distinguished by its simple but effective “Isolastic” engine-mounting system that allowed for the needed increase in displacement without the associated increase in paint-shaker vibrations. The Commando’s rakish leaned-over engine was largely a visual update to the engine, although Norton also claimed an improved center of gravity and increased space for carburetors and airbox.
So for vintage biking fans, the Norton Commando has it all: decent power, classic good looks, a great soundtrack, and tons of aftermarket and community support. All it really needs is a bit more poke and something to make it just that bit more exotic so it stands out in a crowd.
Kawasaki have gotten a lot of ink recently with the introduction of their supercharged H2 and H2R bikes. While there have been a number of production turbocharged motorcycles, supercharging generally seems to suit motorcycles a bit better: the performance is more linear and the plumbing is much simpler.
Simply: a supercharger is generally belt-driven off the crankshaft and works as an air pump to cram more fuel/air mixture into the engine than would be available at normal atmospheric pressure. Technically, a turbocharger is also a type of supercharger, but is driven by exhaust gas instead of a belt, meaning power is determined by throttle-opening and revs. Turbos are a great way to get “free” horsepower, but since turbos are driven by exhaust gasses, you have to route all that air from the exhaust to the turbo and back into the engine. Something that’s generally not such a big deal with cars, but often difficult and very inconvenient on a bike.
This particular Norton 850 Commando is fitted with a period Drouin supercharger unit. Period tests saw north of 100hp, up from the approximately 60hp produced by the stock unit. Early versions used a side-valve carburetor that apparently leaked, so this later, fuel-injected setup should be a big improvement.
From the original eBay listing: Supercharged and Fuel Injected 1974 Norton 850 Commando for Sale
A 1974 Norton 850 SC Commando with 13,669 original miles. A series of tasteful custom features adore this wonderful street bike. They include the following; Competition Fairing, Full instrumentation Package, Wickedly Beautiful Black Paint, Corbin Gun Fighter Seat, Carry On Tool Kit, Light Weight Front Fender, Back Dated & Vented Front Drum Brake, Custom Oil Lines, Twin Oil Coolers and the incredibly Rare Drouin Super Charger with Fuel Injection.
The Drouin unit, Slide Throttle Fuel Injection unit and the Instrument Package were after market item that could have been purchased in the 1970’s, through the Norton dealer. The Drouin Super Charger and the Slide Throttle Fuel Injection unit are fully operational and produces amazing and quick 100 HP. The Fuel Injected Slide Throttle system was the very last iteration of the Drouin Super Charged series intake systems, therefore, being the most advanced and powerful. Upon riding this custom Norton there is sense of amazement in the additional torque and power that comes from the bike. It runs properly and smoothly. The shifting in precise and positive. The brakes are quite ample in bringing this bike to a halt. The tire have some age on them, but are quite usable. The fuel tank interior has been cleaned and sealed.
The rear fender has some small dimples and a little discoloring. There is some very minor pitting on the wheels, a 1/8″ hole that had been drilled through the front, between the forks. Otherwise, this Norton 850 SC was shown recently at the prestigious “Riding Into History” Motorcycle show in May and was judged as a first runner up in the all Norton class, next to a very well known, twin engine Bonneville Norton. A spare Super Charger Drive Belt is included with the sale of the Norton, as well as an original Drouin Super Charger Manual.
Drouin superchargers are desirable period mods should add significantly to the performance and value of this bike. Bidding is very active at this point, with several days left on the auction. I’m thinking this would make for a possibly fiddly, but very rewarding motorcycle. I’d love to hear that classic British twin noise with a supercharger whine laid over the top!