Yamaha's Motorcycle Detective

Hanai-san | Solving Motorcycle Mysteries

To most, it was a beautifully preserved example of a half-century-old DS6-C. To Hanai-san’s experienced eye, however, it was a story waiting to be told: a tale of parts gathered across continents, whispers of a bygone era, and a puzzle that a lucky find would eventually help solve.

Hanai-san is more than a restorer; he is the Sherlock Holmes of the motorcycle world. With sharp observation and an ability to deduce history from detail, he pieces together the lives of bikes and their owners using only clues from the parts he inspects.

While a motorcycle’s overall appearance might hint at its past, it’s the subtler signs—patterns of wear, replaced parts, and tiny imperfections—that Hanai-san reads like a book. For him, every restoration project is an irresistible investigation. Though the DS6-C sat silent in the workshop, its aged components held secrets, ready to share their story with someone skilled enough to listen.

As the lead restorer at Yamaha Communication Plaza, Hanai-san has worked his magic on countless motorcycles that now grace the museum’s three floors, which total 6200 square meters of Yamaha history. For every machine on display, several more are awaiting their turn—either undergoing meticulous restoration or resting in storage.

  
The DS6-C was slowly disassembled with Hanai-san carefully examining and cataloguing each part as it was removed. “Even when I first saw the bike, I could tell that it was in very good condition and still capable of giving its owner a fun time in the saddle,” Hanai-san revealed while working on the machine. “But for Yamaha Motor to preserve it as one of its historical assets, the small amounts of rust would need to be removed, and the peeling paint restored.” As he removed each part, Hanai-san discovered evidence of decades of loving maintenance and regular riding, both done with skill and care. “I’ve been doing this job for a long time, and I can usually tell just by looking at a bike how the owner rode and maintained it. For example, a booster has been fitted to the lights’ electrical system, which tells me the owner often went for long-distance rides that went into the night. And because the tyres are evenly worn, I can tell the rider enjoyed a lot of cornering through mountain roads away from the city; this piqued my interest about who the owner was.”

The fuel tank, curiously devoid of rubber knee grips, immediately caught Hanai-san’s attention. “I’ve never seen a tank like this,” he mused. “The speedometer, marked in miles, and the engine number confirm it is an export model, yet no records explain the missing grips. Maybe it’s a custom modification carried out somewhere along the way.” 

Hanai-san also pointed out some of the differences between the standard DS6 and the scrambler-inspired DS6-C, including the high-mount exhaust that required different muffler brackets, the engine guard, and the modifications to the frame to relocate the rear brake adjuster which explains why the DS6-C uses different brake cables than the DS6.
Looking through the transmission Hanai-san discovered traces of rust on unused areas of bearings. “This tells me that the bike had been ridden regularly and well-maintained over recent years, but prior to this, it had been stored for a long period,” he explained. Disassembling the engine revealed oversized pistons and cylinders, indicating extensive modifications for sustained use. “Whoever owned this bike rode it hard and often,” Hanai-san declared with a smile.

Further scrutiny unearthed bespoke craftsmanship. Muffler mounting brackets, fabricated by hand, hinted at an owner who prized function over factory-standard replacements. The torque rod for the rear brake and a custom-made inspection window for the oil tank also spoke of a skilled hand at work. “There’s love in how this bike has been cared for,” Hanai-san remarked. “The muffler heat shields have been re-chromed, and the other components are nicely polished. The quality of work makes it present beautifully, but it’s not over the top like a show bike that never gets ridden.” It was this attention to detail that kept Hanai-san coming back to the missing knee grip pads on the tank. “Somebody like that wouldn’t purposefully remove the tank’s knee grips,” he said. “That’s left me thinking it was probably a modification by an owner prior to the current owner.”

As the restoration neared completion, Hanai-san solved the mystery of the rubber knee pads with a chance discovery. A guidebook from the 1969 Tokyo Motor Show was discovered, and it featured a DS6-C without rubber knee grips. “It’s not clear whether it was an export model or a later model,” Hanai-san explained, “but it is proof that having no knee grip rubber pads on the tank was an original specification by Yamaha.” The decision was made to keep the tank that was fitted to the bike when it first arrived at the Communication Plaza. “We had prepared another tank with rubber knee grips, so if we had not made this discovery, we would have fitted that one. The guidebook was an excellent find and a good example that there is always something new to learn.”

Saito-san’s story

While Hanai-san and Saito-san had never met prior to the restoration of Saito-san’s DS6-C, when the pair met at the Communication Plaza to look over the beautifully restored bike that was on display for the first time, Hanai-san felt like he was meeting an old friend. It was obvious right away that the two men shared a similar passion for Yamaha motorcycles. Like his Yamaha counterpart, Saito-san was meticulous with his record-keeping throughout the ownership of the bike. In addition to being a fellow engineer, he was also able to share a detailed history of the bike and confirmed all Hanai-san’s assumptions based on his detective work.

Saito-san first fell in love with the DS6-C as a high school student in Japan, mesmerised by the sparkling machine’s chrome brilliance, but it was an expense he was too young to afford. Decades later, a fateful encounter with the same model in California rekindled his passion for the bike. “When I was in my forties, I was transferred to California for work, and one of my friends there owned this DS6-C,” he explained. “Upon seeing the bike I admired in my youth, it felt like a fated encounter.” He begged the owner to sell it to him, and when he finally relented, it was shipped to Japan, where it was ridden regularly for the next 25 years, lovingly maintained to keep it in excellent condition. 

Under its chrome and paint, Saito-san’s DS6-C carried 25 years of memories. The bike had been more than just transport; it had been a companion throughout his forties and beyond, cherished and meticulously maintained. The decision to donate a favourite machine from his collection to the Communication Plaza was not an easy one to make. 

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Saito-san confirmed many of the observations made by Hanai-san and revealed that he had machined replacement parts when the originals were unavailable. “I enjoy polishing my motorcycles,” he admitted, “but I don’t like buffing parts to a mirror finish. I kept the original look intact.” It was a sentiment that resonated deeply with Hanai-san, who prioritises preserving the authentic spirit of each bike during restoration. Saito-san also confirmed he had replaced the pistons and cylinders and was impressed that nothing had slipped Hanai-san’s attention to detail.

Regarding the bespoke muffler mounts, Saito san revealed that when he bought the bike, one was already missing. “I thought it would look bad with just one, so I took the remaining one off, but then I lost it,” he said. “The vibration started to bother me, so I made two new ones myself. I also made the torque rod for the rear brake, and I made a new inspection window for the oil tank because the plastic had cracked from age.”

Looking at the restored tank Saito-san was also happy that the knee-pad mystery had finally been solved. “The lucky break with the Tokyo Motor Show guidebook means that the restoration can be admired knowing that the bike presents exactly how it rolled off the Yamaha production line.”