Yamaha’s 1960s street scramblers are an example of how the Japanese bike makers were starting to get their machines just right. Steve finds a rare YM1 and does what he loves to do – give it a blast
As the Yamaha organisation found its feet following tentative exports to the United States of America, it realised that two things substantially aided sales: successful racing results and an active development programme.
Racing at the Catalina GP, a tarmac and dirt event, had brought Yamaha a significantly wider audience. Fumio Itoh may only have come sixth in the 1958 race but he’d also beaten some seriously big names and brands at the same time.
There’s even a newsreel of the event where the narrator makes light of the strange Japanese Y-A-M-A-H-A and its rider: history would show his cynicism was desperately misplaced.
Spurred on by this and other successes, Yamaha had a rolling programme of development which soon saw their twostroke twins rapidly developing.
Initially based around the German Adler MB250, the firm swiftly took the design to levels of performance few would have credited. The early YDS1 and YDS2 were well received stateside but the pivotal sea change came when the third iteration, the YDS3, arrived on both sides of the Atlantic.
Arguably this is the bike that cemented the Yamaha brand with customers and spoke volumes about the mind-set of the Yamaha R&D team. Fast, rev happy, reliable, sure -footed and, crucially, crammed full of fun and character, it was pretty much an instant hit globally. Sharper than both comparable offerings from Honda or Suzuki the YDS3
rapidly became the fast rider’s missile of choice. However, following the old American adage that there’s no substitute for cubes, fans of the bike were clamouring for more power.
Yamaha came late to the party that was motorcycle construction and had some catching up to do. Without the same level of resources or experience as their rivals, the company did things very much their own way and it’s a facet of the firm even to this day – Yamaha has always been somewhat maverick. With neither the resources nor finance to design a totally new machine from scratch, the YDS3 was effectively reworked, but in Yamaha’s own unique way.
Whereas others might simply go for a bigger bore, Yamaha opted to both increase piston diameter and increase the stroke length, thereby creating the 305cc YM1. Installed in the existing 250 twin’s chassis the firm effectively had a new model without all the attendant hassles of making something totally novel.
The bike and its progeny would act as a stopgap for just a few years, giving the firm vital breathing space that would then allow them to go to the next level. Sales of the YM series enhanced Yamaha’s reputation and, most importantly, added an extra revenue stream to their finances. The YM1 was never officially imported to the UK but CBG has a rare opportunity to sample one – and it’s a peach.
If you know something of your early Japanese strokers you might very well reckon the red and white twin to be a YDS3 when viewed from the right-hand side. It has similar panels and overall profile to the 250 and the only obvious giveaway is the 305 badge tacked onto the left-hand side, almost as an afterthought. The main colour (Candy Red in this instance) covers most
of the tank, both oil tank and side panel, the tops of the shock absorbers, half of the front suspension as well as the headlamp body. Aesthetic counter points come courtesy of both the white tank panels and the black/ white seat combination, the latter being something of a Yamaha signature design through the mid-Sixties.
The bike’s appearance is unquestionably conservative but at this juncture the Japanese stylists were finally doing their own thing rather than slavishly following German motorcycle designs. A pair of decent sized guards, the rear being valanced, keeps the worst of the road dirt off the rider whilst the deep chainguard, in theory at least, keeps oil off the bike’s rear end.
The YM1 was produced to be a practical machine, hence the enclosed suspension at both ends, oiling points along the various cables plus grease nipples on the brake pivot arms and the gear linkage. Fitted with a 12-volt dynamo, points and coils the bike’s electrics were standard, dependable
Yamaha fitments from the likes of Mitsubishi and Hitachi.
The striking speedo-cum-tacho gauge in the headlight follows the market trends of the time. This initially takes a little getting used to but, blissfully, both needles swing in the same direction unlike some Japanese bikes of the period. Our test bike runs a full set of genuine Yamaha indicators; these would have been a dealer fit option when the bike was new. Having purchased the bike to be ridden on the road, the current owner managed to track down a set of indicators and lenses fairly easily via trade contacts and the VJMC. The actual indicator switch on the left bar was an extremely lucky internet find from the USA costing just over £100 including shipping and taxes… well sometimes you just have to have the right parts!
Moving the YM1 around ready for our road test it feels low and weighty, which is pretty much standard fare for the Yamaha twins of the period. Iron barrels add to the overall mass and the frame is a relatively chunky piece of engineering in its own right.
Firing up the elderly twin is a fairly straightforward affair once the lever of the unusual twin union tap is pushed downwards. With the choke lever flicked down on the pair of Mikuni VMs it only remains to turn on the ignition via the switch in the right-hand side of the headlight binnacle.
For the uninitiated the kick-start is mounted on the left, an artefact of the bike’s German ancestry, but once sussed out it’s easy to use. One kick from hot or two from cold has the 305cc motor running and the choke can be flicked up fairly quickly ready for the off. Ah, yes, here’s one of the YM/YDS foibles; they all run engine speed clutches which take a little getting used to. Just like many MZ singles the entire clutch mechanism is going around at engine speed and, for the unwary, it all feels just a little
alien. Too little revs and the motor bogs down momentarily which in turn prompts the rider to add revs, which then seems to make the clutch feel grabby. Once your brain is suitably recalibrated the clutch is no longer an issue, until you forget next time!
Once underway, the bored and stroked motor pulls well and gets a surprisingly fast wiggle on. Gear changing requires a firm foot and touch of feel; YM gearboxes apparently can be a tad on the notchy side but once again it’s all part of the learning process of getting to terms with a machine from more than 50 years ago.
The bike can be hustled along at a fair rate of knots and even if the suspension is primitive by today’s standards it’s still both safe and entirely capable. At speed the bike is light yet not in the least bit flighty; its mass keeps it planted on the road in ways RD350 owners can only dream of!
Before getting too gung ho with someone else’s pride and joy it’s always a damn jolly good idea to get a feel for the brakes. Having ridden and owned Yamahas of similar vintage I’ve more than an inkling of how they’re going to behave and I’m not wrong. Both brakes are more than up to the job and only, perhaps, feel just a little bit wooden but I’d put that down to the period OEM linings. The front is a fairly substantial twin leading shoe device with its partner being a conventional SLS unit. What impresses me here is just how good the
“Yamaha came late to the party that was motorcycle construction and had some catching up to do. Without the same level of resources or experience as their rivals, the company did things very much their own way”