Suzuki AC50: a little scrambler with a character of its own

Suzuki’s sporting fifties have a clear family tree. In 1963 the company launched the Sports 50 M12, according to Suzuki its first light sporting 50 cc. Despite the name it was not meant only for enthusiasts: it was designed to suit commuting as well as leisure. It had a telescopic front fork, waterproof brakes and a raised exhaust.

In 1967 came the Sports KS50, with a backbone frame and Suzuki’s CCI lubrication. In that system a separate oil pump feeds two-stroke oil directly to key points in the engine, such as the crankshaft and connecting-rod bearings and the cylinder, instead of mixing oil into the fuel. A year later, in 1968, the Sports AS50 appeared: a light sports machine styled after the Grand Prix racers, with a V-shaped backbone frame, a high-revving engine giving 6 PS at 9,000 rpm and a five-speed return-shift gearbox. Suzuki quotes a top speed of 95 km/h for the Japanese AS50 of the time.

That same year Suzuki launched the Scrambler AC50 in Japan. According to Suzuki it was essentially the same as the AS50 in performance and mechanics, but equipped as a proper scrambler. It received braced handlebars, footrests that fold back automatically after contact and a raised exhaust. The tank was shaped so the rider could grip it well with the knees on rough ground.

What made the AC50 especially interesting was the range of parts around it. Suzuki offered many kit parts to convert the scrambler into a motocrosser. That suited the spirit of the time: young riders wanted not only to ride, but to modify their machines and experiment off road.

At the heart of the AC50 is an air-cooled 49 cc single-cylinder two-stroke with a rotary disc valve. According to Suzuki’s Japanese data it has a 41 mm bore and 37.8 mm stroke and produces 6 PS at 9,000 rpm, with torque of 0.5 kgm at 8,000 rpm. Power goes to the rear wheel through a five-speed return-shift gearbox. Both wheels carry 17-inch tyres.

The rotary disc lets the engine breathe at the right moment, independently of piston movement. This gives a lively, high-revving engine but also demands good crankcase sealing and correct lubrication. On a scrambler, dust, water and vibration add to the load, which makes healthy carburation, ignition and secure exhaust and frame mountings all the more important.

In 1970 Suzuki updated the AC50 in Japan. The main difference was safety equipment: a larger headlamp, a safety lamp, a front-brake-operated stop light switch, an indicator buzzer and side reflectors. The described engine data stayed the same. Suzuki gives this model a dry weight of 74 kilograms and a 1,185 mm wheelbase, against 1,160 mm for the 1968 version.

Suzuki also explains why the scrambler was becoming more important: demand was shifting to machines that could be enjoyed off the paved road too. So the company simultaneously released kit parts to convert the AC50 easily into a motocrosser, as well as kit parts for the transmission.

These data concern the Japanese models. We do not include export names or year letters for European versions as long as a conclusive primary source is missing. The cards below are therefore not an exhaustive worldwide list.

For a young rider in the late sixties, the AC50 was an invitation to leave the road. With its high exhaust, sturdy handlebars and tank shape it looked like an off-road machine, and thanks to the kit parts it could become one. It was an everyday fifty and a step towards motorsport at the same time.

Today the AC50 is a less common classic that appeals to enthusiasts through its combination of sporting Suzuki engineering and scrambler looks. Precisely because many machines have been modified or used off road over the years, a good restoration takes patience and care.

Determining the correct version takes more than a tank badge. Record frame and engine numbers and the available documents, and compare brakes, lighting and lubrication system with the documentation for the country and year. Kit parts or later modifications may have changed a machine considerably. We do not adopt a full specification sheet from a related model.

During a rebuild we look at crankshaft sealing, cylinder and piston, carburation, ignition, lubrication and the condition of the frame and exhaust mountings. Discuss beforehand whether the existing paint and patina should be kept or a different finish is preferred.