Seeing a vintage BSA Gold Star motocross bike in competition led to the discovery and modification of this off-road racer
Story by Greg Williams
Photos by: Amee Reehal
As important as earth is in supporting life, for plenty of motorcyclists, it has played another critical role – many riders got their first taste of powered two-wheel freedom riding on dirt.
Take, for example, Hans Christensen of Calgary. He and his brother, Soren, grew up on a farm near Lethbridge, Alta. In the early 1970s, dirtbikes figured prominently in their youth as they tore around the family property. Eventually, the boys gained enough experience to become quite competitive in organized motocross races aboard 125 cc and 250 cc Husqvarna machines.
But when Christensen’s two young sons entered the picture, he quit the racing scene and sold all the dirtbikes. It wasn’t long, however, before Adam and Jason were listening to Dad telling stories about dirtbiking. Plus, they’d often travel to the family farm, where there were still a couple of bikes. Not surprisingly, the two siblings soon expressed an interest in riding.
A New Generation of Riders
“In the mid- to late 1990s, [Adam and Jason] had Japanese dirtbikes and I had a KTM to chase them around,” Christensen says. At that time, the family was living in California and there were some good off-road riding areas where they could get out and hit the trails.
Then, in 2001, after moving back to Calgary, the Christensens took up motocross racing, participating in events at Wildrose MX Park and other tracks in Alberta.
“It was just the competition that was fun, and the boys did well in some of their events,” Christensen says. “But then we got interested in vintage-class racing. I’d always really liked the old stuff, and a fellow I worked with was into vintage racing and I think that filtered through to me.”
Vintage MX Club
The three of them joined the Vintage MX Alberta club, a group of off-road enthusiasts hosting race events around the province. According to its website, the club has seven machine classifications, with enough diversity to accommodate just about every motocrosser that was manufactured prior to 1990.
Christensen picked up pretty much where he’d left off, acquiring a few 1970s-era Husqvarna two-stroke dirtbikes. His youngest son, Jason, however, was interested in old four-strokes, as he’d seen Steen Hansen competing aboard his BSA Gold Star. The single-cylinder overhead-valve British racing machine made an impression, and Jason started searching for a similar motorcycle to campaign.
What he found for sale south of Seattle was a circa 1953 Matchless G80CS. The Christensens talked to the seller via phone, looked at a few pictures and bought the Matchless without actually seeing it in person. The motorcycle was shipped to the Montana/Alberta border, and that’s where they picked it up.
The Matchless G80CS (C for Competition and S for Spring frame) model is a machine that can trace its lineage to 1935 and pre-Second World War motorcycle production of the G3 model.
After the war, Matchless offered the G3L, a 348 cc single; and the 497 cc G80. Stroke in both engines was the same, at 93 mm, but the larger-capacity powerplant had a bore of 82.5 mm. Overhead valves were operated by pushrods, and the four-speed right-foot shift Burman gearbox was separate from the crankcase. Dry-sump lubrication saw oil carried in a right-hand-side oil tank.
Matchless added the Competition, or C, models to the range in 1946, and rear suspension was added in 1949 to the road-going machines. In 1950, the engine received an all-alloy top end, and then the following year, the rugged G80C became the G80CS with the addition of the rear swingarm. Ignition was by Lucas magneto, which in 1952 moved from behind the cylinder to in front, and the carburetor was a
Flat Tracker to Motocrosser
As purchased, the Christensens’ circa 1953 Matchless had been set up by the previous owner for flat-track racing. That included the low-level exhaust and a small fibreglass fuel tank. The rear wheel is thought be from a Bultaco, while the 35 mm forks were made by Metal Profiles. Better known as MP, Metal Profiles was a precision engineering firm that supplied lightweight telescopic forks to many manufacturers in the British motorcycle industry. The front hub is from a Suzuki TM400.
With fluids checked and gas in the tank, it didn’t take Christensen long to work out the starting drill. But after a few laps around the motocross track, it became apparent some changes were necessary. First, the oil tank mounts cracked. Christensen cut and formed from aluminum a new tank to sit above the rear engine mounting plates, and…