Four-stroke singles: Honda C100 and derivations
Enthusiasts of all forms of motorcycles have conversations that tend to revolve around the same kind of topics. Steve Cooper looks at one of the most popular, and comes up with the perfect answer.
Ask a room of two wheel aficionados what’s the best motorcycle ever made and you’ll get as many answers as there are motorcyclists present. Pose the question about engines and the variation in replies drops dramatically, with parallel British twins coming near the top.
But, potentially, this is the wrong answer. If you rephrase the question to read – 'what’s the most successful engine in the world?' then there really can be only one reply. That it’s a four-stroke single might not be such a surprise... but when this is qualified by the engine’s capacity of just 49cc, eyebrows tend to be raised.
The C100, and all subsequent spin-offs, owes its existence to a fact-finding trip undertaken by Soichiro Honda and his right-hand man, Takeo Fujisawa, in mid1956. The tour of European manufacturers and dealers confirmed in their minds that non-enthusiasts who happened to use a powered two-wheeler were effectively being short changed.
Most, if not all, the small machines were variously either two-stroke and/or bicycle-like in construction. Although cost-effective for the firms that built and sold these utilitarian devices, the customer was expected to put up with a serried raft of compromises ranging from premixing two-stroke, marginal brakes, variable build quality and poor reliability.
Seeds sown
The pair concluded that what was needed was a novice, non-motorcycling, ownerfriendly two wheeler that demanded little of its purchaser, was easy to ride and simple to service. And from these criteria were distilled the seeds of the C100 motorcycle.
Together, Honda and Fujisawa condensed their ideas with two overriding criteria – the bike had to be a four-stroke and the finished machine had to be simple to build and generate a profit. Reliability, ease of access, longevity and simplicity were givens.
Over the next 18 months, sketches, drawings, blueprints and prototypes began to take form. Despite their earlier successes with overhead cam motors the decision was made to run with a simple pushrod design, again targeted at reliability and ease of maintenance. A big end was adopted using a pressed-up crankshaft that ran on roller bearings. It was apparent that the average potential customer was intimidated by the presence of a clutch and manual gear lever