Here’s something you don’t think about very much, unless it’s not working: your cam drive. As most of us ride modern motorcycles with dual overhead cams, we take for granted the smooth, quiet and reliable nature of the cam chains and tensioners that keep our camshafts opening and closing valves many thousands of times every minute, mile after mile, year after year.
It wasn’t always so. Honda is now well-known for making single and dual overhead cam motors, most famously the CB750, but back in the early ’60s the company’s engineers struggled with getting chain-driven cams to run as precisely and reliably at high rpm as the gear-driven equipment on the factory racers. Honda had been using overhead cams in its small-displacement street bikes, but to dominate the world motorcycle market it needed a way to inexpensively and reliably provide big-bike power, power that would shame and humiliate the older OEMs like Triumph, Norton and Harley-Davidson.
This bike is one stop on the way to the famed CB750, the model that paved the way for Japanese dominance of motorcycling, a dominance that only now, almost a half century later, is starting to crack. You won’t find it in any spotters guides and you certainly won’t find it parked outside your local Starbucks. It’s a rare and interesting 1962 Honda CR72 street bike owned by Ron Mousouris. It’s the only one known to exist.
It looks a lot like a CB72 Hawk, but vintage-Honda enthusiasts will point out the unique motor. The motorcycle is the result of Honda’s R&D department fitting a one-off CR72 race motor into a CB72 Hawk chassis, probably for testing and evaluation purposes. According to the Classic Japanese Motorcycle Club‘s Allan Seikman, who showed me the bike at the recent Clubman’s Weekend at the San Jose fairgrounds, the engine ( serial number 300001) looks very much like a CR72 unit, complete with magnesium bits and distinctive cam covers for the dual camshafts. It is fitted with a six-foot-long cam chain, and some parts look like those off the later CB450.
This bike’s history is murky and the story I got may be hearsay—but it’s all the information I could find. Seikman tells me the motorcycle was used as a development testbed in Japan and then sold to a U.S. serviceman stationed there. He raced the bike in Japan and then in the U.S. after he returned home. At some point, the motor “blew up,” and the guy sold it to a Honda dealer, where it languished for decades.
Enter Ron Mousouris, owner of the Benly Shop, where he restores vintage Hondas. He acquired the bike, and since it was not in the state it was in when it left Honda’s R&D department many years ago—to say the least—he replaced everything but the original engine. That means the bike you see here is, except for the unique powerplant, in essence a replica—but that doesn’t diminish the visual impact of the project. Stock CB72 and other vintage components were carefully located, modified and restored to produce a close recreation of how the bike originally looked. See some of the build thread here.
Regardless of originality, the historical import of this bike made it thrilling to see in person. Reliable overhead-cam engines led to the CB450, CB350, CB750 and other smooth, fast and reliable bikes like the Z1 and GS750. Thanks go out to guys like Allan and Ron for keeping history alive.