Tractable, stylish in the GPZ family way, and tough enough for a hard-worked stroker
The Kawasaki AR125 in restricted and even unrestricted form
POWER-CAPPING LEARNER laws that came into force in the UK in 1982 could have meant disaster for new riders, and even for the UK motorcycle business.
Luckily certain motorcycle manufacturers, understanding the importance of the British market, had a ready response to the 12bhp 125cc learner limit. That meant making 12bhp liquid-cooled 125cc two-stroke singles as fun and stylish as they could be. Yamaha made it to market first with the 1982 RD and DT125LCS but Kawasaki weren’t far behind with the 1983 AR125.
Capable of topping 78mph in the hands of a dedicated, prone rider – perhaps with a hint of a following wind – the restricted AR125S imported to our shores were as good as the competition. So the full-house 20bhp models (sold alongside the restricted bikes) certainly delivered more, but the stifled UK learner bikes did well working with what they had.
Much of the engine’s flexibility was down to Kawasaki’s combined rotary and reed valve induction system (or RRIS as Kawasaki’s acronym designated it). This allowed much of the available power to be delivered across the rev range. Reed valves in the left side of the crankcase took care of low-speed running and once fully open, it was the business of the rotary valve to control induction. Where the use of a rotary valve normally meant mounting the carb on the side of the engine thereby making it wider, the AR’S Mikuni VM24SS was mounted slightly offset to the left of the back of the barrel. The inlet tract went through the crankcases.
The result was a decent spread of power from 4000rpm, through the peak power point at 8500rpm with an over-rev to the redline 2000rpm beyond that. That made the AR more tractable than the Yamaha LC. You could even be fooled into believing the
AR had more than its 12 restricted ponies.
Then there was the visual appeal. The AR125 looked a lot like Kawasaki’s GPZ big-bike offerings and also boasted some of their tech. The cast gold and silver alloy wheels looked the business. Even if the rear brake was merely a drum, the front at least was a hydraulic disc with a single-piston sliding caliper. The bikini fairing added loads of grown-up kudos too, even if it did turn with the ’bars in a manner disconcerting to anyone more familiar with a frame-mounted fairing.
At the back was a basic version of Kawasaki’s Uni-trak monoshock system. With everything in the engine bay finished in black – even the Mikuni carb on early models – the AR had a stealthy air.
Through specifying a 12-volt electrical system, Kawasaki was able to fit a halogen headlight to the AR and adult sophistication also extended to the clocks in their black-plastic moulded binnacle with a speedo, rev counter and temperature gauge, plus a full complement of idiot lights. A lockable flap on the tail unit offered just enough space for 10 Benson.
Of course in the fickle word of style, the AR wasn’t seen as the hot ticket for long among fashion conscious youth. During the AR’S eight-year production run there were many new contenders for the 125 crown; the Suzuki RG125, Honda MBX, NS and NSR125, Yamaha TZR125, Gilera RV and, in the AR’S last year, the Cagiva Mito.
One potentially discouraging aspect of the AR to some sections of UK youth was the difficulty in derestriction. Candidates for change to unleash full power include the disc valve, barrel, jets and exhaust. In other words a good deal more trouble than it’s worth. Enjoy it for what it is. If it’s slower than you remember, that’s probably just down to your greater contribution to a less favourable power-to-weight ratio today.