ACCORDING TO MY MATE GEORGE, WHO bought a Yamaha RX-S 100 on a whim many years ago, there’s 12 horsepower and then there’s TWELVE horsepower. He was frankly somewhat taken aback by just how pokey the little 98cc single was – and he wasn’t the only one with that opinion either. For anyone who had previously sampled the factory’s similarly branded RS100/RS125, the RX-S was a bit of shock. Graced with less mass and increased power, the RX-S was like an angry ferret compared to the fluffy RS100 bunny. For a brief period from the mid-1980s through to the late 1990s, the RX-S 100 encouraged youngsters to have fun while putting a big grin on the faces of long-term commuters.
Miniature power house
Many of Yamaha’s earlier two-stroke singles were peppy disc valve models that came with a reputation for both ruggedness and performance. As good as they were, there was an issue – cost. Disc valve engines require more machining and consume more parts in order to deliver. Absolutely not an issue when you’re building race bikes, but when it’s a small bike aimed at a cost-conscious market, every Yen counts. With the adoption of reed valves, Yamaha found
