YAMAHA AS3
It’s the rev-happy pre-reed-valve tiddler twin that always brings a grin, says our Scoop!
It’s early 1970 and Yamaha have been happily pedalling their eighth-of-a-litre pocket missiles for threethe model ye years in various guises. Formerly known as the AS1, theh bike has be been upgraded subtly to deliver the AS2 with revised tin-ware and a (slightly) better front brake. Both bikes are now looking a little old so the firm decides to rework the design and, cleverly, future proofs a profile that will ultimately be around late into the decade. The ‘all new’ AS3 borrows heavily from the older analogues, but also sports a raft of differences – many cosmetic, but not all. Some are obvious, such as the new aesthetics, whilst others are tucked away inside the engine.
Key to the revised motor are alloy barrels with gulley or Z ports machined into the rear faces of the cast-in-iron liners that are matched by new pistons and larger fins to the cylinder head. The bike will be the second smallest two-stroke twin of the 1972 Europa range and earn itself a well justified reputation for being something of a miniature projectile. The AS3 will run for just one model year before morphing into the RD125 of 1973, which will itself later be miraculously transformed into the disc-braked, coffin-tanked RD125. In this guise the bike will remain on the sales lists until the new 125cc learner laws see it pensioned off in favour of a liquid-cooled single.
In some European countries a 125 was the largest motorcycle you could legally ride as a learner and the AS3 has, justifiably, earned semi-mythical status as being one of the early 1970s’ hot shots. Although not quite as feisty as the later, even more highly-strung, Suzuki GT125, the AS3 is certainly rev-happy. Tiddler sports twins aren’t known for their torque but, in the real world, an AS3 is probably easier to ride than some of its peer group, providing you’re happy to nail the throttle.
Although not really delineated clearly by Yamaha, there are actually two sub-variants of the AS3. The earlier examples run seamed silencers and smaller tank characterised by a fuel tap that fits via a double-ended alloy nut to a spigot. The later versions have smooth silencers and a fuel tap that fits on via two 6mm screws inside the tap body. Dig around on forums and you’ll find some folk getting really sniffy over these differences and arguing that only the earlier examples are ‘true’ Europa models. In the real world simply finding a viable AS3 should really be seen as reward enough!
Here in the UK the 125cc category machines were often perceived as the poor man’s learner machine and the bikes were generally recklessly abused, ridden into the ground or transformed into production racers with varying degrees of success and viability. Unless you were minted, the accepted/ best route was to buy an AS3 GYT (Genuine Yamaha Tuning kit), which consisted of a Hitatchi ignition system stator-plate assembly and rotor; twin coil packs; special cast alloy barrels with a steel liner; single ring racing pistons; a gear ratio kit comprising of six sprockets; expansion pipes spring mounted at head; larger Mikuni VM carburettors; folding footrests; new foot controls and gear/brake levers; 28mm clip-on handlebars; Yamaha TZ style twin pull throttle cable; and a 16000 rpm redline tacho. This little lot got you as close as possible to an over-thecounter, Iwata built, TA125 proddie racer. Thus equipped, countless teenagers would try to emulate their race hero Kent Andersson, who bagged two 125cc world titles in 73 and 74.
The phrase, ‘If I had to explain you wouldn’t understand’ could have been written for the AS3. It’s one of those conundrum machines that is irritatingly greater than the sum of its parts. On a purely technical level the later RD125 totally out-classes its piston-ported predecessor, yet ride the RD125 and the AS3 back-to-back and tell us here at CMM which one is full of soul and which one feels strangely sanitised.
The AS3 asked you to wring its neck, encourages you to maintain corner speeds, positively encourages last-minute braking, and yet remains happy to come back for more. The drone of the inlet system, the muted purr of the motor and the scream of the exhausts all conspire to have you mentally ear-holing a works YZ623 or OW-15 around Silverstone’s original Club corner. They really are rather addictive and those that own them tend to hang on to them, but if can scrounge a ride, grab the opportunity with both hands because only then will you appreciate why, just occasionally, less really is more!