“Even back then, I thought of it as a kind of tradition, but you could say Yamaha certainly was a manufacturer that put a lot of importance on the rider’s evaluation,” recalls Akiyasu Motohashi,
a rider that any fan in that era of motorcycle racing knew.
Motohashi competed in World GP races in Europe as a Yamaha factory rider in the 1960s. He was one of my highly respected seniors and someone I looked up to when I was younger. He was a standout racer at the time because he was more of an intellectual and had graduated from university. I remember the final round of the World GP in 1966 at Fuji Speedway in particular.

“To Yamaha engineers, since the machine is ridden by a person, fulfilling the requests of the rider as much as possible was always the fundamental approach. Despite the often abstract requests of riders for ‘this’ or ‘that’ about machine handling, the engineers would always figure out some way to provide a solution, and they did so with incredible speed, too. Their teamwork was almost abnormal in the way they would all concentrate together on the work at hand,” said Motohashi. “When I entered the Yamaha team, I came to think of this as normal, but when I found out later how it was for riders on other teams, I realized that the relationship Yamaha had with its riders was something special. For other manufacturers, racing was more of an extension of the machine testing program and most of the riders that were on the track racing for them were test riders by profession. But, the only ones that could ride Yamaha’s race bikes were fully contracted racers.” When I asked him when he first “understood” handling, he said, “The first time I really ‘experienced’ what handling meant was with the 1962 TD-1. When I came down hot through the final corner at Suzuka on high-grip tires, the bike felt like it was flapping in the wind. When I went through on tires that weren’t so grippy, there were no problems and I put up a good lap time. That was when I first really understood the difference between ‘good’ and ‘bad’ handling.”

His words reconfirmed what I had thought; the riders that were actually racing on those bikes of the time knew the importance of handling. Yamaha’s engineers listened to their comments and built up their knowledge and expertise of motorcycle handling from early on. The RD05 that came out a few years later represented the full embodiment of the knowhow they had gained. As Yamaha’s first 250cc 4-cylinder race machine, the handling problems that inevitably emerged were solved with specific countermeasures that were steadily implemented on the bike.

Motohashi continued: “The RD05 had good power from the switch to four cylinders, but that also made it heavier and it had handling problems of its own; the air-cooled twin RD56 was sometimes actually faster around the track.

Thinking back on it, the aluminum undercowls on the TR-3 and TZ350 I used to race would also scrape the track. The cowls were fit so snugly with the engine that it was like they were touching, and despite knowing that the cowls would scrape the asphalt, Yamaha lowered the center of gravity anyway.
“Now that I think about it, the RD05 was also fitted with a mechanism that made the caster angle adjustable. They didn’t alter the wheelbase but instead made it possible to adjust the caster angle for low-speed or high-speed corners.”

This surprised me because I’d never heard of such a device; the pursuit of handling performance had already come this far by 1965 and 1966. This was surely one of the main reasons Yamaha’s cornering performance was so good back then. “Yamaha was definitely fast in the corners. Even when most of the other manufacturers had switched to 4-cylinder bikes, the 2-cylinder 125cc RA97 was still competitive. The deciding factor was the torque Yamaha engines had. Everybody else was ignoring torque and aiming for top speed, so their powerbands got narrower and they had to add more transmission gears to use those narrow powerbands. Yamaha’s focus was always on good corner exit acceleration, and the key to having a high corner speed was to have the torque to power out of that corner. Some manufacturers fielded machines with 12 gears, but the RA97 started with 8 and ended with just 9.” This battle in the 125cc class saw 4-cylinder machines from Suzuki and Kawasaki with 14 gears facing off against Yamaha’s RA31 and its 9. When I started racing, I was with a Kawasaki-based team and I watched my seniors struggling to ride machines with redlines over 15,000 rpm but with a powerband less than 1,000 rpm wide using 14 gears—what an incredible difference in machinery from Yamaha.
(Continue to Part 2)