Yamaha RS100

. This was an RS100 (itself a 1976 improvement upon the design of the original reed-valved 96cc RS100 that was introduced to the United Kingdom in September, 1974, and to the US in November, 1974) with a front disc brake and a tachometer, and was replaced

With the square-stroke, 98cc RX-S (with part numbers coded 31J), a major update on the RS design (with substantial changes particularly to the cylinder, head, and induction, and the points ignition replaced by Yamaha Capacitor Discharge Ignition) which was to form the basis of the Escort-distributed…

With a new chassis and shorter wheelbase, with the same primary reduction ratio as the RX100 but with a taller final reduction. The RX-Z was launched with sportier bodywork and produced 12 bhp (8.9 kW) at 6,500rpm.

With the same engine as the RXZ but using the same chassis as the RX 100 or RXG. The RX135 saw a moderate success due to its refined power output and better fuel economy.

Yamaha launched the RX135 5 speed with a large catalytic converter muffler (silencer). It's had a higher compression ratio and different port dimensions.

. The final variant was a 4-speed RX 135 with a smaller catalytic converter silencer, classic rx100 like tank stripes and twin pod speedometer with white dials which was sold very briefly