POPS HAD GOD HANDS
Pop Yoshimura was in at the start of the ’70s superbike boom, tuning the hell out of Suzukis with his bare hands. Here’s how he established his legendary name
The life, times and unparalleled skills of the man behind Yoshimura’s success
Hideo ‘Pop’ Yoshimura became the world’s most famous motorcycle engine tuner as the direct result of a near-fatal air crash. The teenaged Yoshimura was drafted into the Japanese military during the early days of World War II and was nearing the end of his fighter-pilot training when the accident happened.
“My father wanted to be a fighter pilot, had passed all the tests and was ready to go,” says his son Fujio. “But then at the end of his training his plane had an engine failure, so he had to jump – but his parachute didn’t open until just before he hit the ground, it barely saved his life. He was discharged from the navy pilot school because he had lung damage, but his dream was still to fly airplanes, so he became a flight engineer. He studied four-stroke gasoline engines, like the Zero fighter engine, from the bottom to the top.
“After the war there were a lot of motorcycles running around, so he became interested in them and started working on engines. He had studied engines so closely during the war that there were no competitors with half his experience. He had so many crazy ideas and could challenge so many things, all by himself.” Many of the motorcycles running around Japan were ridden by some of the 300,000 American servicemen who occupied the country from 1945-52. Pop established his first, tiny shop near a USAF airbase, where the dollar-rich Americans bought bikes and asked Pop to make them go faster. He soon became the go-to engine tuner and founded Yoshimura Motors in 1954, a year before Suzuki even launched its first proper motorcycle.
Yoshimura gained its first laurels with Honda machinery. In 1964 a Yoshimura-tuned CB77 won the Suzuka 18 Hours race (yes, 18 hours, not eight). However, Yoshimura wasn’t quite ready for the big time. The increasing domination of two-stroke race bikes kept things quiet, until Honda unleashed its CB750 in 1968 and Kawasaki its Z1 four years later.
Finally, Pop could go to work. In 1971 a Yoshimura CB750 led the Daytona 200, until it broke a cam-chain. In the USA the superbike revolution was go and Yoshimura’s renown spread across the country. Pop knew a golden opportunity when he saw one, so in 1973 he moved to Los Angeles where he established Yoshimura Racing, which later became Yoshimura Research & Development of America.
Neither Pop nor Fujio got out much. Father and son spent endless days and nights in the dyno room and workshop, Pop grinding camshafts by hand while young Fujio looked and learned. “After the CB750 we ran Kawasaki Z1s for a while,” adds Fujio, who became company president a few years before his father died in 1995. “We got lots of horsepower out of them, but they wobbled so much we were just scratching our heads – what could we do? Then Suzuki came out with the GS750. We discovered this motorcycle in late 1976. That’s when we knew – wow, Suzuki are serious!”
Not long after that Suzuki’s top four-stroke engineer Etsuo Yokouchi visited Suzuki America in LA. Yokouchi was the mastermind behind the GS750, Suzuki’s first four-stroke, and its big brother, the GS1000. “We were very lucky,” recalls Fujio. “One day
‘POP GROUND CAMS FROM BILLET AND, FILE IN HAND, PROFILED THEM TO HIS SPEC’
we made a call to Suzuki America and he was there; it was kind of a coincidence. We made an appointment, had a face-to face-meeting and made a verbal agreement, looking into each other’s eyes and went from there. In those days that was good enough.” Suzuki wanted Yoshimura to help them go racing with the GS750 and the soon-to-be-launched GS1000, because although Suzuki had just won their first 500cc world championship with the RG500 two-stroke, they knew little about going racing with four-strokes.
The new partnership was an immediate success. Yoshimura GS1000S won the 1978 Daytona superbike race, took first place in the first-ever Suzuka 8 Hours, monopolised the podium of the 1979 Daytona superbike race and won the 1979 US superbike championship. Superbikes were big news for the first time; Honda America entered the class in 1980 with Freddie Spencer, and Yoshimura imported factory Suzuki rider Graeme Crosby for the Daytona superbike race. Croz won the race from the back of the grid, after he had infringed a minor rule in his heat race.
These were the Wild West days of superbike racing, when engineers and mechanics transformed innocuous street bikes like the GS1000 into tyre-shredding monsters. These transmogrifications weren’t easy to bring about, requiring endless hours of engine tuning and chassis redesigns. “We had a lot of fun with the old road bikes because there were so many areas we could put our ideas into,” says Fujio. “To me, the 1980s was the peak. There was so much engineering going on back at the shop, because after every race we needed to do something different for the next race.”
Don Sakakura, who joined Yoshimura R&D America in 1980, also remembers those mad days and nights with fondness. “It was a really neat experience,” says Sakakura, who is still with the company. “We learned many different crafts and skills because we were converting what were almost touring motorcycles into motorcycles that could go around a race track. We were looking for levels of engine performance and durability that the bikes weren’t designed for. That forced us not only to find more horsepower but also find weak points. When we discovered weak points it was hard work to make sure they didn’t affect the way the bike went around the track, which got us thinking a lot more.
“It was enjoyable, being deep, deep into those areas: hands-on grinding, welding, bending, whatever you had to do to get the job done. They were skills I was taught by Pop, Fujio and Suehiro Watanabe [who became head of Yoshimura in the US when Pop retired and Fujio
returned home to run Yoshimura in Japan]. I’ll never forget the camshaft development and the ideas that Pop had – file in hand, grinding a cam from billet and profiling the cam to a spec he liked!”
And it wasn’t just frame tubes that Yoshimura and their American rivals at Honda and Kawasaki were bending. US superbike regulations demand standard frames, but the showroom frames of that time were dangerously unfit for purpose, especially when it came to resisting the huge loads imposed by hurtling around the Daytona banking at 170mph. All the teams had no choice but to bend the rules by using replica frames fabricated from stronger, higher-quality tubing. They were all at it and the scrutineers turned a blind eye. Yoshimura came to dominate everything. In 1981 Wes Cooley and Crosby rode their GS1000S superbikes – Fujio’s all-time favourite – to a one-two at Daytona, then Crosby used a Yoshi-powered factory Suzuki TTF1 bike to win the Isle of Man Classic and F1 TTS. Two years later a Yoshi Suzuki TTF1 bike won the Suzuka 8 Hours and the endurance world championship, with Richard Hubin and Herve Moineau on board. While Pop and Fujio did the engines, Suzuki looked after the TTF1 chassis, which was based on the RG500.
There wasn’t much that Pop and Fujio didn’t do to the
dohc 16-valve GS1000 engine to make it so dominant: highly polished cylinder head, forged pistons, exotically-timed cams, special crankshaft, enlarged valves, lighter tappets, titanium valve-spring caps, 31mm Keihin smooth-bore carbs, Kokusan CDI ignition and so on. The result? From 100bhp at 8700rpm to 150bhp at 10,500rpm.
But the father/son partnership wasn’t all peace, light and race victories. “Pop had god hands, but he also had his ideas and I had mine!” Fujio recalls. “We had a big fight during the first Suzuka 8 Hours. We were having so many problems with the clutch, but he had his way of fixing it and I had mine. We had a big fight! I was ready to go back to the States. Then Wes Cooley came up and said: ‘Please stay, we’ve got qualifying in two hours!’” As the 1980s economic boom got underway, bike sales rocketed in the US and Japan, engorging factory superbike budgets. Suzuki couldn’t afford to keep up with Honda, Kawasaki and then Yamaha, who came to dominate Yoshimura’s two biggest races of the year: Daytona and Suzuka.
But all that changed with the launch of arguably the first real superbike: the GSX-R750, which arrived in the US after it was launched in Europe in 1985. “Prior to that we were racing the GSX750 [with young punk Kevin Schwantz onboard], which was more of a street machine that we had to modify ourselves because the factory wasn’t that involved,” adds Sakakura. “The first GSX-R was a ground-breaker. We had come from the GS750, the GS1000 and the GSX750 and then all of a sudden, wow, we’ve got a super-light aluminium chassis and a super-powerful engine. The power-to-weight ratio was incredible, so it was really more of a race machine, not like the street motorcycles we’d had before. For me, the GSX-R was the most important stage in learning about racing – and that’s when the Suzuki factory became serious about racing, so the association between Suzuki globally and Yoshimura became very strong, plus the engagement between Suzuki America and Suzuki Japan became very active.”
Although Honda had unleashed their incredible RC30 World Superbike homologation special three years after the GSX-R750’S European launch, Yoshimura had one of its best years in 1989. Jamie James won the US Superbike crown aboard the latest GSX-R and Doug Polen took the All-japan TTF1 and TTF3 titles aboard a Yoshi-powered GSX-R750 and GSX-R400. That year’s 8 Hours engine, a 749.7cc unit, produced 140bhp at 13,500rpm, while the 756.2cc US superbike engine made 143bhp at the same revs.
Yoshimura Suzukis have won all kinds of races and championships around the world, but the company’s year always revolves around two main events: Daytona and the Suzuka 8 Hours. “The 8 Hours is my favourite race,” says Fujio. “In Japan we spend most of our time and effort on the 8 Hours because we must get a good result. The reason we do the All-japan Superbike Championship is to develop our 8 Hours bike!”
Fujio remains heavily involved in the firm, but misses the good old days. “Back in the early 1980s, all you needed to go racing was a rider, a few mechanics and a team manager, whereas now I need five or six people to run one goddam motorcycle!” he laughs. “Everything is so specialised: tyres, electronics, engines, chassis and so on. This can mean that the satisfaction you personally get from racing is less, because your responsibility is divided by five or six because that’s how many people you need to run the motorcycle.”
‘WE WERE LOOKING FOR LEVELS OF ENGINE PERFORMANCE AND DURABILITY THE BIKES WEREN’T DESIGNED FOR’