When the FIM introduced a new 50 cc class to the World Championship in 1962, Honda entered with the single-cylinder RC110. That machine proved uncompetitive against the two-stroke machinery fielded by Suzuki and Kreidler, and an updated variant, the RC111, was introduced for the Isle of Man TT but still fell short of the pace set by rival two-strokes. Honda engineers immediately began work on a fundamentally different approach: a twin-cylinder engine in the 50 cc displacement bracket.
Engineer Shoichiro Irimajiri played a major role in developing the RC112. The twin-cylinder concept was taken further with a large-valve derivative designated the 2RC112. Neither variant was refined enough to contest the World Championship during the 1962 season, but the RC112 reached readiness in time for the domestic All Japan Championship. The Suzuka Circuit itself was a Honda-owned facility completing its inaugural year of operation, making the meeting a significant occasion for the manufacturer on home soil.
At the All Japan Championship race, Honda fielded the RC112 for riders Tommy Robb and Naomi Taniguchi. Luigi Taveri sampled the twin in practice but elected to race on the single-cylinder RC111 instead. The race initially appeared set to be dominated by Ernst Degner on a Suzuki RM62, who built a commanding lead before crashing at the 80R corner on lap four. Degner's retirement handed the lead to fellow Suzuki rider Michio Ichino, who in turn crashed on the final lap, opening the door for a dramatic conclusion.
Tommy Robb pulled away from a three-way battle with Hugh Anderson and Isao Morishita to take the victory for Honda on the RC112. Taniguchi finished joint fourth alongside Seiichi Suzuki. Robb was effusive about the twin's qualities after the race: "Very smooth, excellent power and the handling was superb. It was also an excellent riding position and didn't feel as cramped as the old single."
Despite the race win, Honda's engineers acknowledged that the RC112 was still inferior to the rival Suzuki RM62 in outright performance terms. Development continued on both the RC112 and the 2RC112 into early 1963, when work also began on a new four-valves-per-cylinder engine designated the RC113. The RC112 programme was wound down shortly afterward.
Honda's internal evaluation concluded that the 50 cc class offered the poorest prospects for results relative to investment. Facing budget constraints in the 1963 season, the company chose not to contest the 50 cc World Championship, redirecting resources toward the larger and more visible classes where its multi-cylinder technology could deliver more prominent victories.
The RC112's single race appearance at Suzuka in 1962 marks an important milestone in Honda's technical history. The engine's DOHC twin layout in the 50 cc class — a configuration that required extraordinary precision in its miniaturised construction — demonstrated Honda's engineering ambition during its formative years in international racing. The machine represents an early example of the philosophy that would later drive Honda's development of increasingly complex multi-cylinder configurations across all Grand Prix classes throughout the 1960s.