Yamaha AT90 twin, 89cc (36.5 x 43mm) 8.2ps @ 8000rpm Yamaha AS-1D twin, 124cc (43 x 43mm) 15ps @ 8500rpm (also CS-1E 180cc) Yamaha AT90 continued Yamaha AS-1C twin, 124cc (43 x 43mm) 13.8ps @ 7500rpm Yamaha 90HS-1 twin, 89cc (36.5 x 43mm) 10.5ps @ 8000rpm Yamaha AS-1C continued (plus the 180cc CS-2E) Yamaha AS-2 twin, 124cc (43 x 43mm) 15ps @ 8000rpm Yamaha HX90 twin, 89cc (36.5 x 43mm) [email protected] 8000rpm (styled like RD125) Yamaha AX125 twin, 124cc (43 x 43mm) 15ps @ 8500rpm Yamaha RD200 twin, 195cc (52 x 46mm) 22ps @ 7500rpm (based on AX125) Yamaha TA125 twin road racer, 124cc (43 x 43mm) 24ps @ 12,500rpm Yamaha AX125 (AS3 in Europe), RD200 continued Yamaha RD125A/B twin, 124cc (43 x 43mm) 16ps @ 9500rpm (disc in Japan) Yamaha RD125D twin \ (coffin tank), 124cc (43 x\43mm) 16ps @ 8500rpm \
Yamaha RD125E continued, (new styling)
Yamaha RD125 with coffin tank and cast-alloy wheels Yamaha RD200 with coffin tank and cast-alloy wheels Yamaha RZ125 (RD125LC) liquid-cooled single launched
The top speed figures at MIRA suggest that the gearing might have been low, but for practical purposes it was fine for road use. On the 1000-yard timing straight, the bike revved beyond the red line to 10,000rpm in top gear as I chinned the tank racirg style, clocking an average of two opposing rtns of 77.65mph.
For the performance, the RD125 was pretty economical to run. At a constant 60mph, it recorded 69mpg, but in general use with more acceleration the average was just under 60mpg, for a range of about 150miles.
The brakes, with a 6.5-inch twin-leading-shoe drum up front, were as hugely effective as their appearance would suggest, stopping the bike in just 25 feet from 30mph, when anything under 30 feet was regarded as good. Though powerful enough in the dry to lock up the front wheel, it was still safe enough to use effectively on wet surfaces.
The RD125 wasn't a model of perfection though. While cog swapping was crisp, the linkage had some slack and would stick in the change from second to third on occasion. The rubber transmission dampers in the rear wheel hub were also slack, making a smooth take up of the drive difficult. I also got the impression that the bike had suffered from poor treatment during running in: a slight seizure made the power tail off at 9400rpm and there was a rattle at the lOOOrpm idling speed.
During the 1200 mile test the bike needed more than the usual amount of attention to keep it at its best. The plugs had to be replaced, the carburettor jets unblocked, the battery topped uc - an awkward exercise - and the chain adjusting. Oil consumption was high, at 200 miles to a oint (or v/hat would be about 350 miles to a litre, and a range of 550miles). The ignition switch between the instruments also jammed later in the test. None of this diminished the fun of riding tie RD125, more so its thrills could be enjoyed without breaking speed limits or spending too much on fuel (a gallon cost just 42p at the time).
But once we'd become accustomed to the higher fuel prices, the appeal of a 125 declined and the 200 began to make more sense. Even so, Yamaha upgraded the RD125 with the coffin-style fuel tank, added a disc brake and later adopted cast-alloy wheels.
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