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Clymer Manuals Matchless G9B Vintage Motorcycle Video G9 AJS Model 20

Clymer Manuals got an up-close look at Rick Taylor’s 1958 Matchless G12CS at the 2013 HoAME Vintage Motorcycle Show.

Clymer on the lift didn't have to go far to attend the 2013 Heart of America Motorcycle Enthusiasts club 22nd Annual Vintage Motorcycle Show. Classic vintage antique motorcycles motorcycle bikes British, German, Japanese, Italian, European, American motorbikes were all on display. Manufacturers included Honda, Yamaha, Suzuki, Yamaha, BMW, Harley Davidson, Vincent, Triumph, BSA, Norton, Brough Superior, Indian, Cushman, Vespa, Laverda, Puch, Lambretta, MV Augusta, Ducati, Matchless, Zundapp, Moto Guzzi, AJS and more. There were 100% perfect restorations, bike ridden in, a few trailer queens, full-on customs, cafe racers, choppers, bobbers, trials bikes, dirt bikes, road racers...any type or style motorcycle you could imagine.

As we all know, the markets for motorcycles in Britain and the United States have long been different. In American motorcycles are purchased for sport, and performance is the name of the game; in the UK, on the other hand, they have been traditionally used for basic transportation, making virtues of low cost and economical operation. Over the years AMC responded to this difference by selling in the U.S.A. some versions of the Matchless and AJS which never appeared on the domestic market--indeed, even the existence of some of these variants is unknown to British enthusiasts. While all AJS and Matchless motorcycles are desirable pieces of machinery, the US-only versions are especially attractive from a collector viewpoint.

G45/G9/G80 - In the mid-fifties Cooper Motors, the California-only Matchless importer, brought in a very few bikes consisting of the G45 road racing twin engine in the G9/G80 frame. Apparently the objective was to provide a machine for favored riders that would be more competitive in AMA racing than the standard or race-kitted G9 twin. Gearboxes with kickstart levers were fitted to conform to AMA requirements. The engines were simply stamped "G9/230 to 240", suggesting that no more than eleven of these machines ever existed.

This variant was brought to my attention by John McCoy of Britalia Motors in San Jose, California. While they are not now fitted, John says it came with rearsets and a tach drive.

Anyone fortunate enough to acquire one of these bikes should be able to obtain spares through standard sources, as both G45 and G9 parts appear to be available without too much difficulty.
G9B/20B - In 1954 and 1955 all AJS and Matchless twins imported into the United States were apparently the 55Occ "B" variants, easily identified by the letter B in the engine serial number after G9 or 20. The extra 50cc was obtained by the simple expedient of boring the cylinders out to 69mm compared to the 500cc bore of 66mm. An extra 3 horsepower, 32 versus 29 at 6800 rpm, was claimed for the modified twins. The driveside crankcase half was possibly different as well, as it has a different part number, but I have not been able to identify the difference. The "B" variants were offered in the standard "Clubman" or roadster version, but a "CS" version with 21" front wheels, alloy fenders, and other fittings from the CS singles was also available.

Hundreds of the B variants must have been brought into the US, and they are frequently encountered. I have lots of old sales and advertising literature showing this motorcycle, and also have a parts list supplement detailing the differences in it and the standard 500cc twin. When I was in Russell's in London last summer they had 550cc pistons and barrels on sale, but barrels could also be obtained by the simple expedient of boring out a 500cc barrel. Other parts should be available from standard sources.

Matchless as a company goes back to the turn of the century, and Brough Superior used Matchless engines because they were the best of the best. This changed in 1938 when Matchless was consolidated with AJS to form Associated Motorcycle (AMC). The new company may have been one of the first major badge engineering firms because the only difference between an AJS and a Matchless was the badges on the tank.

The AMC motorcycle that had a winged “M” on the tank was the G9, and the corresponding AJS was called the Model 20. First offered in 1948 the standard 498cc AMC engine produced about 29hp and would move you along in the mid 80’s. What makes the G9B different is 50 small CC.

US market was the life blood to the British motorcycle industry. When British bikes failed to sell in the US, British motorcycle manufactures failed. AMC wanted to give the US market what it has always asked for and tried to do this with 50cc. Those extra cc gave only 3 more hp to top out at 32hp from the original G9. The recipient of many of these bikes was the Southern California Dealer Coopers Motor.

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