Yoshimura history – 03
Tracing the path of the world-class engine tuner from Kyushu to Tokyo and from Japan to US, through the three generations of Yoshimura family.
As the miraculous combination of Pop, Gannosu and the Honda Hawk nurtured young talents, Kyushu became the center of the national racing scene.
Pre-1964 Days: The Boys with Talents
To get a glimpse of the weekly races held in the neighboring “America” on the base, a crowd of young Japanese people had clustered along the steel fence every Sunday afternoon, after the base chapel service. More and more Japanese were becoming members of KTA.
In November 1960 came the Honda Dream Super Sports CB72 (Hawk), a bike that changed both Hideo “Pop” Yoshimura’s life and the Japanese motorcycle racing scene forever.
It was sensational —- as stated on its brochure, the CB72 “cannot be run in top gear below 70 kph”. While Triumph, BSA and BMW then were all using the conventional over-head valve (OHV) mechanism on their bikes, the 247 cc CB72 and its big brother, the 305 cc CB77 (Super Hawk) which came out in 1961, both featured a four-stroke parallel twin cylinder engine with an over-head camshaft (OHC). Pop initially had not taken much interest in the bike since he was disappointed with the hard-to-tune engine design of its ancestor, the Honda Dream C70, but then he found out that CB72/77 had a much stronger crankshaft with only one press-fit, instead of two with the C70. Additionally, there were two different crankshaft options to choose from: the 180-degree Type I crank with irregular firing intervals suitable for high rpm uses and the traditional 360-degree Type II crank suitable for low to mid rpm uses. Pop obviously preferred the Type I which produces less vibration at high rpm and can deliver more power.
Best of all, they were much cheaper than European imports. The CB72/77 gave young Japanese an opportunity to leap over the fence of Gannosu —- and some of those men and boys had real potential to become elite racers.
The first Yoshimura employee was Fukuo Kuradome. Pop first met Kuradome at a drag race at Ashiya Air Base in which Kuradome was riding a C77. Pop hired him not only as a racer but also as a mechanic and salesman. He was fast on a bike, good at speaking broken English, great at getting along with people, and much better at collecting bills from American troops than Pop. In fact, Pop had never collected unpaid bills by himself.
Yoshimura’s first ace rider Fukuo Kuradome, pictured here with a Yoshimura-tuned Honda CB72. Kuradome was one of the few Japanese members of Ashiya Timing Association and was working at a local Honda dealer as a factory manager before Pop hired him. He not only became a Yoshimura rider but also a great salesperson as well as the acting manager of both Yoshimura Motors and KTA. Behind him is a signboard reading “Kyushu Balcom Motors” that indicates Yoshimura Motors’ side business at that time as a foreign motorcycle dealer.
Then came two more very talented boys: Fukumi Koutake and Kuniomi Nagamatsu. They were both born in 1944 and had something truly brilliant inside of them. Koutake however was a troublemaker at first, making his parents wring their hands in despair, so Pop made Koutake live in his house —- even so Pop often had to go to the local police department to pick Koutake up —- teaching Koutake life lessons. Pop warned young racers not to waste their talents, and trained them hard in the style of Imperial Navy Flight School, with daily physical exercise including early morning 4 km run, 100 stair runs and stretch sessions sprinkled in between. This kind of physical training was unusual for motorcycle racers by the standards of the time, but it was somewhat similar to that practiced by professional racers today, since they are now considered to be athletes. The young racers also went for a riding practice several times a week. It was about a 200 km round trip along the coastal road (from Hakata to Kanzaki and back) following Pop on his BSA and it took around 2 hours. Their “racetracks” were located on U.S. military bases and were open only on weekends, so the public roads were the only place they could practice riding.
Fukumi Koutake on #3 CB72 and Kuniomi Nagamatsu on #100 CB77. The two became Yoshimura riders when they were teenagers. Pop nurtured them at Gannosu and later introduced them to ex-GP racer Kenjiro Tanaka, who in turn recruited them to the Honda-sponsored racing school (known as Kenjiro School) at Suzuka Circuit.
With the help of advice from Kuradome, both Koutake and Nagamatsu gradually became better racers. Years later Koutake confessed, “I surely would have become a serious delinquent if I hadn’t met Pop and gone through his tough training”. Koutake’s experience with Pop might have inspired him. After retiring from his racing career, he launched the Team Koutake RSC to nurture future racers, including the late Daijiro Kato, Tohru Ukawa and Akira Yanagawa.
Koutake tended to manage untamed machines by instinct alone. Nagamatsu on the other hand had radical but clever —- knee down, butt slightly off the seat —- riding form.
“I just figured it out myself. That was the only way I could’ve gone around those slippery, dirt and paved corners at Gannosu, at high speeds on a bike with almost no lean angle,” recalls Nagamatsu. His prominent riding style was seen in local races in the early 1960s, nearly 10 years before the late Jarno Saarinen shocked the world with his “hang-off” in GP races.
Yoshimura-CBs were quick. Kuradome had also developed a new riding technique and a handsome “lean-with” style which made him known as Surtees of Japan. On his helmet is a map of Kyushu.
Another star rider at Gannosu racetrack was Akira Matsumoto, a tall lad, who was famous for his sharp riding style rivaling that of Nagamatsu. He was a member of Team Fukuoka Honda —- then the chief rival and comrade of the Yoshimura riders —- and was coached by their team leader Kiyoshi Kamogawa, with whom Pop met at Itazuke.
On Honda CR72 production racers, Koutake (at left) and Nagamatsu (at right) at Gannosu. Nagamatsu was recruited by Honda to become a development rider for the CR72. The photo (likely taken some time after 1962) proves Honda’s trust in Yoshimura, as the supply of the CRs had been strictly regulated.
Pop disclosed to the riders at Gannosu every modification he had done to the bikes. Matsumoto remembers, “every part of his engines was polished like a mirror, and every bike he built had lightening holes all over its engine and chassis.” However, Pop had never modified a crankshaft before then, other than buffing. Team Fukuoka Honda suggested that the lightening of the crankshaft would increase the engine speed and power, but Pop told them to leave it stock, believing that it’s already optimized for the best performance possible. As an experiment, Fukuoka Honda tried the idea on their CB72, and much to their surprise won the next race against Yoshimura-CB72.
Perhaps inspired by this incident, Pop then began to lighten the crankshaft to the extreme and afterwards the Yoshimura-CB72 became far faster than the Fukuoka Honda’s CB72. After all, mass-production motorcycles in those days still had plenty of room to be tuned for more power. Pop showed his lightened crankshaft to the Team Fukuoka Honda, since they were friends and he had nothing to hide. Pop also took his formula for high-lift camshafts one step further. Instead of just reducing the base circle diameter of stock cam, the new method is implemented by fusing stellite alloy onto the cam lobes, before the grinding process, to produce even more valve lift. The CB72/77 also provided a great opportunity for Pop to try different tuning methods.
Kiyoshi Kamogawa rounds a corner on his CB. He was a clever, celebrated ace rider of Yoshimura’s rival team Fukuoka Honda, as well as one of the leaders of Japanese riders in the KTA. Brilliant mechanics at local Honda dealers came up with some great ideas Pop hadn’t thought of, such as the lightening of the crankshaft.
Still, he knew that something was missing. In addition to motorcycle tuning, Pop also worked on the tuning the people and environment surrounding the racing scene. In the late March of 1962, he made a trip to Tokyo to meet Fumito Sakai, the Chairman of MCFAJ (Motorcycle Club Federation of All-Japan) and the publisher of Motorcyclist magazine, to ask him to hold a clubman race in Kyushu. Although Pop had never met Sakai before, KTA had been a MCFAJ member since 1959.
Since its launch of the 1st All-Japan Motorcycle Clubman Race at the Asama Highland Motor Vehicle Test Course in 1958, the MCFAJ had become a crucial element of the Japanese motorsports scene. Pop presented the allure of the racetrack at Gannosu, along with the increasing popularity of the races held by KTA, and added that many new entrants are coming from outside of Kyushu. Sakai at that time has not yet decided the location for the Clubman Race of that year, but as the most of MCFAJ members reside in and around Tokyo, the presentation was not enough to convince him. Pop revisited Sakai again in April for the same request.
Two months later, in June 1962, Sakai traveled to Kyushu to visit Yoshimura Motors and to have the third meeting with Pop. The decision was finally reached. Gannosu —- the home for Pop, Amereican troops and all the motorcycle racers in Kyushu —- was chosen to host the “All-Japan” event in which the domestic manufacturers would also enter factory teams.
The 5th All-Japan Motorcycle Clubman Race was due to be hosted by MCFAJ and KTA on the 14th and 15th of July. Again, it was the selfless passion of one man, Hideo “Pop” Yoshimura, that shaped a monumental moment within the history of Japanese motorsport.
Kuradome holds a clean line through the 90-degree left (the 2nd) corner at Gannosu. The deep peg scrapes on the road surface still remain to this day. Gannosu Air Station (Brady Air Base) provided its service roads for the racetrack.
Yoshimura aces with a Honda CR. From left to right: Nagamatsu, Kuradome, a customer, Koutake. They were cheeky and kept getting into trouble in town, but when Sunday afternoon came, they hit the racetrack at Gannosu, started the bike, opened the throttle wide open and everything was alright. No one knew what their futures might hold.
Published on July 20, 2018
Stories and photos supplied by Yoshimura Japan / Namiko Moriwaki / Road Rider Archives
Written by Tomoya Ishibashi / Edited by Bike Bros Magazines