Retrospective: Meguro Junior S3 250: 1957 – 1958

story and photography by Clement Salvadori

[This Retrospective: Meguro Junior S3 250: 1957 – 1958 was originally published in the September 2011 issue of Rider magazine]

Pretty good-looking motorcycle, this OHV 250. Look down at the right-side engine case and you might expect to find the stacked rifles of a BSA…instead of that highly stylized letter M. M—for Meguro, one of the earliest of Japanese motorcycle manufacturers, dating back to the 1920s.

This quarter-liter model was called the Junior, while its 350 sibling was known as Rex. The first Junior was the S2 of 1955, and then came the S3. The engine had a bore of 65mm, stroke of 75mm, making it a torquey little bike. Long strokes were definitely favored with these small four-strokes, with the BSA C12 of the same years as this Meguro model having a 63mm bore, 80mm stroke—and said to put out 11 horses at 5,200 rpm. A Japanese-produced Amal carburetor feeds the combustion chamber, with the S3 reputedly developing 10 horsepower at 4,000 rpm, though that seems a trifle conservative…along with a rather optimistic speedometer that ran up to 160 kph, or 100 mph. The separate three-speed transmission shifted on the right, like a good British bike, and like the British the Japanese had decided to ride/drive on the left side of the road.

Again, in good British tradition the cases were split vertically, which often meant a little oil leakage. It was a dry-sump engine, with an oil reservoir on the right side. The primary case was tin, which required a thick cork gasket to keep the oil inside. The rear chain was totally enclosed, which provided both longer chain life and much cleaner running.

The engine was bolted into a cradle frame, with a telescopic fork at the front, plungers at the back. The rider’s seat was sprung, adding to the comfort. Wheelbase was 56.5 inches, and the weight was a hefty 403 pounds…the BSA equivalent weighing almost a hundred pounds less. The wheels were 19-inchers, with drum brakes, standard for the era. A magneto sparked the plug, while a Mitsubishi generator powered the lights, and kept the six-volt battery charged. An observant eye will note the presence of turn signals…in 1957. Turn signals were required in Japan on all 1958 models, and optional earlier on. Fully valanced fenders served to keep the worst of the road grime off of the rider.

Operation was simple. The handlebar choke-lever would be used when the engine was cold. Otherwise, turn on the fuel petcock, prime the carb, a kick of the starter with the clutch lever pulled in to free the plates, let out the clutch, put the key in the slot in the headlight cowling, and after one or two kicks the rider should be on his or her way. This was good transportation, with little sporty about it.

But along with the specifications of this S3 we should look at the history of Meguro, which had a pretty good run. Japan had proved itself the equal of Europeans when they defeated the Russians in the Russo-Japanese War of 1904-’05.

However, in the automotive world they still felt themselves behind the talents of the round-eyes, and after the huge earthquake of 1923 which destroyed most of the area around Tokyo (including much of Japan’s industry), they looked to Europe and the United States for ideas.

The distant past can be a trifle hazy, but in 1924 a fellow named Osama Murata founded the Murata ironworks, and was manufacturing bits and pieces for the several small concerns that were building automobiles and motorcycles; then Murata began cobbling together his own machine, using proprietary engines. In the ’20s and ’30s several dozen backyard engineers were building motorbikes, from the Aero Star to the Yamato, but who knew who Murata was? While nearby was the famous Meguro raceway; in 1928 he changed the name of his company. In 1937 he began building his own engines, with the first complete Meguro motorcycle, the Z97, being a very British-looking OHV 500 single. This, much to Murata’s pleasure, became the official motorcycle of the Tokyo police.

The Great Depression had hit Japan as hard as it did the rest of the world, but Japan’s solution was to expand its influence, building the Greater East Asia Co-Prosperity Sphere over the objections of the Koreans and Chinese. And then came World War II, Hiroshima and Nagasaki, and a very devastated nation. Which picked itself up and began re-industrializing.

Meguro Junior S3 250: 1957 - 1958
Year/model: 1957 Meguro Junior S3 250. Owner: Allen Siekman, Ben Lomond, California.

Meguro continued to produce the 500cc Z97 while also busying itself developing some smaller, less-expensive 250 and 350 engines, still based on the European designs. The first of these 250s was designated the S2, appearing in 1955.

But in the ’50s, Honda and Yamaha and Suzuki were all developing brand-new motorcycle models, technically far more sophisticated than the English and American bikes whose technology was already 20 years old. Kawasaki Heavy Industries, which was building big ships and the like, had tentatively entered the motorized two-wheeler market in the mid-’50s with a scooter, and then under the name of their Meihatsu subdivision developed several motorcycle models with two-stroke engines, a 125 single and 250 twin, which did not sell very well.

The Kawasaki name had clout, which Meihatsu did not, and having the fastest bike on the block would give it even more clout. Meguro was also producing the biggest-bore motorcycles in Japan, 500 and 650 twins that copied British engineering, and a deal was struck in 1961, with Kawasaki gradually absorbing Meguro. One of the last badged Meguros to be built was the S8 250 single in 1964, with Meguro on the gas tank, Kawasaki on the engine.




  1. Hello

    I’m from Brazil and I have a bike Meguro junior S3 1958. I would like to reform it, but it’s missing some parts. Can you help me find parts? Here in Brazil we do not have information on this bike. If you can not help me, please tell me someone who can.

    Best regards



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