YAMAHA YL1
Scoop waxes lyrical about a 100cc twin that really thinks it’s a sports bike!
A buyer’s guide.
Few tiddler twins have the power to excite and inspire like a Yamaha YL1. It may only boast a meagre 97 cubic centimetres, but the bike uses what it has to devastating effect. It really is that special. Top speeds and standing quarter times are all entirely academic; it’s the sounds and sensations of working a YL1 hard that make the experience so special.
The ride is all about getting the most from that small engine, working the four-speed box with its down-for-up shift pattern, maintaining corner speed and only using those vestigial brakes when absolutely necessary. If you like your classic rides torquey and with lots of instant power at you right hand, then skip this article. However, if you want to soak up the very essence of late 1960s two-strokes combined with more than a pinch of race machine DNA, then carry on reading.
There’s just one caveat about the YL1… once you are hooked there is no known treatment! Despite its size, the YL1 is a hugely significant machine spawning numerous other models. The bike’s roots can be traced to 1965 when Yamaha launched the 90cc AT90, which was aimed at attracting Japanese customers who wanted economy and performance in one package. The bike proved to be an instant hit and Yamaha saw a ready market outside of Japan where riders might appreciate a small, peppy, stroker twin.
The AT was bored out to 97cc and the gear change swapped from a rotary to a positive stop four-speed, albeit it with neutral at the top and all gears downwards. The bike ran in pretty much every market from late 1966 through to late 1972 and the bike received various tweaks over that period. The initial 12-volt model ran a simple dynamo that was swiftly gifted two more carbon brushes to enable the dynamo to work as an
electric start, the same as Yamaha’s CS and RD200S. YL1S thus equipped are normally called YL1E on account of the powered foot. To add further spice to the pot there’s also a 6-volt AC generator equipped model. Towards the latter part of its life Yamaha also released a sub-model with chrome front guard along with candy paintwork that extended to the integral rear mudguard. The final iteration was the rather rare YL3. YL2 had already been assigned to a 100cc single. The YL3 finally received a five-speed transmission, which took out the fairly large gaps between the original four ratios.
To add even more confusion to the story the AT90 had been marketed in Japan as the Jet Twin, but in the USA the YL1 (and 3) were marketed at the Yamaha Twin Jet. Even when YL1 sales were at their peak, Yamaha muddied the waters during 1968 by launching another 100cc sports twin that borrowed some of the YL1 and mixed it with aspects of the AS1 125 screamer to deliver the HS1. Graced with five ports rather than the YL1’S three, the bike should have been a bigger seller than it eventually turned out to be. By the end of 1971 the YL1 was looking dated and the decision was made to take the five port technology from the HS1 and combine it with the styling of the all-new Europa range to deliver the LS2. Unfortunately, times had moved on and a 100cc was no longer the novelty it once was. For not a lot more money buyers could get the divine 125cc AS3 with 15 ponies, rather than the 10 of the LS2. Such was the design of the original AT90/YL1 that the basic architecture of the engine formed the bedrock of each and every 125, 180 and 200cc stroker twin from the 1968 AS1 through to the early 1980’s RD200.
A vertically split crankcase allied to four main bearings, synthetic rubber outer seals and central aluminium labyrinth seal and an open bottomed, single down tube chassis became the proven layout for all Yamaha’s sub-250cc sports twins. For many years the original YL1 was looked down upon as a poor man’s classic and the few that were around were virtually ridden into the ground. Times have changed and the small twin has now become hugely collectable both in Europe and in America, and as a consequence prices have risen dramatically to the point where now a running YL1 is empathically no longer a cheap hack. Buy a runner, recalibrate your brain then terrorise the local back roads on Yamaha’s tiddler that, to this day, retains the heart of a lion. You won’t be disappointed.