French upcoming rider Jean-Louis Tournadre took advantage of these changes in 1982 and gave Yamaha its first 250cc world title in almost a decade. In 1983, Yamaha achieved the riders’ and constructors’ titles with Carlos Lavado, repeating that in 1984 for the third consecutive time with Christian Sarron. Regretfully, the improved competition halted Yamaha’s growing streak of titles, despite Yamaha’s efforts in 1985, 1986, and 1988 to upgrade the TZ250’s competitiveness.
Meanwhile, concurrent development saw the creation of the YZR250 (0W82) factory machine using a V-twin engine with a simultaneous firing configuration and twin crankshafts, built as a prototype during advanced development for the YZR500. The YZR250 was entered in both the 250cc Grand Prix World Championship and the All-Japan Road Race Championship in 1986. In the 250cc Grand Prix World Championship, Carlos Lavado secured his second riders’ title, while Shinji Katayama clinched the All-Japan Championship.
In the following years, riders Luca Cadalora, Juan Garriga and Jean-Philippe Ruggia, racing continuously refined versions of the YZR250 were consistently among the front-runners. In 1990, the YZR250 featured a 90-degree V-twin engine with a single crankshaft and coupled-force balancer, which would lead Yamaha to another successful challenge for the 250cc Grand Prix World Championship title.
Due to upheavals in the other Road Racing classes at the end of the 70s, the Endurance World Championship began in 1980, with 1988 marking the start of the World Superbike Championship. In the US, the AMA-F1 regulations for the Daytona 200 imposed limits of carburetor diameter on 2-stroke machines, including the Yamaha TZ750, and in addition allowed 4-stroke 1,000cc bikes to run together with 2-stroke 500cc GP racers.
At the 1980 Daytona 200, where these new regulations were first implemented, it was the TZ750, ridden by Patrick Pons, that won the race. The following year, the TZ750 demonstrated total domination and claimed the top nine places.
A total of 133 bikes entered the 1982 Daytona but it was Graeme Crosby on a YZR750 (0W31) that emerged victorious. Furthermore, in 1983 and 1984 Kenny Roberts rode the YZR700 (OW69) – a modified version of the YZR500 (OW60) – to victory which gave Yamaha its 13th successive Daytona 200 win.
In 1985, Daytona 200 was moved from AMA-F1 to the Superbike class, which used 4-stroke production bikes (750cc or under). That year, Yamaha was not able to participate due to preparation issues. However, Eddie Lawson rode the FZ750 (20-valve, DOHC) to victory – Yamaha’s first major win with a 4-stroke machine.
In Japan, the F750 was replaced by a new 500cc class established in 1981 as the premier category of the All-Japan Road Race Championship. The Yamaha YZR500s, Honda NR500s and Suzuki NGT500s lined-up on the grid for races that were as hotly contested as those in the Grand Prix World Championship, but finally it was won by Keiji Kinoshita on a Yamaha TZ500 production racer. The following seasons saw a constant battle between the Yamaha and Suzuki riders, with both manufacturers coming out on top throughout.