Yamaha TD2

, riding a Yamaha TD2 at Mallory Park 1970 The TD1 bikes had a significant impact on British 250cc class racing in the middle-1960s which was historically contested by single-cylinder engines, some with ageing designs. Some TD1s were overbored to 251cc, thus being eligible for the 350cc class Building on the TD1 successes, the arrival of TD2 together with the TR2 350cc version which could be overbored to around 352cc, making it eligible for the 500cc class, announced the 'death knell' of the traditional 350cc and 500cc class single-cylinder four stroke engines manufactured to 1950s designs The new over-the-counter Yamahas were smaller, lighter with greater maneuverability and consequently easier braking. The engines were simpler to build - but not significantly easier to maintain as four-stroke singles potentially lasted an entire season - offering a small compact unit without the height associated with overhead valves and camshafts. Rod Gould's appearance on the European racing scene with TD2 and TR2 machines (and Buco helmets) secured after a business trip to US was a major factor in the change to two-stroke domination. Gould learned his craft initially by campaigning ageing (1950s design) Manx Nortons around the UK short circuits, with 1960s Bultacos and Aermacchis for the smaller classes. == Racing success ==