Through its success in 1961, Honda was suddenly in a position to be chased by, not chase, the competition. 1962 also saw the addition to World GP racing of the 50cc class, now totaling five classes. Honda embarked on a new challenge, entering machines into every class except 500cc (50cc, 125cc, 250cc and 250cc classes), as the largest team in grand prix racing.
Honda developed the gear train-driven 4-stroke single-cylinder DOHC powered RC110/111 to compete in the 50cc class, but managed to win only one race during the season against fierce competition from the 2-stroke machines. The other three classes were more successful and reminiscent of a champion manufacturer, with 10 wins in the 125cc class, 9 wins in the 250cc class, and 5 wins in the 350cc class: Riders' titles went to Taveri (125cc) and Redman (250cc and 350cc), while Honda secured the constructors' title, showing its strength as defending champion. This year also saw the completion of the Suzuka circuit - Japan’s first fully paved circuit - solidifying Honda’s resolve in its motor sports activities.
For three years beginning in 1963, however, Honda struggled. In 1963, Honda’s complete dominance of the 250cc class was seriously threatened, as it fought every round managing only 4 wins out of 10 races, finally securing the riders' and constructors' titles in the very last round. Honda convincingly won both titles in the 350cc class, with the RC172 winning 6 of the 8 grands prix, but the 50cc and 125cc classes were not so successful, with only 1 win, and 3 wins respectively. In 1964, Honda managed to win the riders' and constructors' titles in the 125cc and 350cc classes with 7 and 8 wins respectively, but that was as far as Honda’s success went for the season. Winning all of the titles became increasingly difficult as competition intensified, with Suzuki entering World GP racing in 1960, and Yamaha in 1961.
In 1966, Honda increased its participation from four, to all five classes, aiming to win the championship in all classes. The season started with Honda upgrading its machines in every class. Luigi Taveri rode in the 50cc and 125cc classes, Mike Hailwood in the 250cc and 350cc classes, and Jim Redman in the 500cc class. The RC116, based on the RC115 with expanded bore for a short-stroke engine, was entered into the 50cc class. The RC149, a short-stroke successor to the RC148, raced in the 125cc class, the RC165 and its successor the RC166 in the 250cc class, the RC173, a further developed version of the RC172, in the 350cc class, and the 489.94cc 4-cylinder RC181, with a bore/stroke of 57mm/48mm outputting more than 80PS, raced in the 500cc class.
Despite problems such as Hailwood replacing injured Redman in the 500cc class, Honda won the constructors' title in all five classes winning an astounding 29 of 37 races, staging legendary races along the way - such as the thunderous Czech Republic Grand Prix at which Hailwood set new lap records and won all 3 classes he raced in. It was the first time ever that one manufacturer dominated all World GP classes, securing Honda’s place in grand prix racing history.