Suzuki’s early 125s

At the start of the 60s Suzuki started to get serious about racing, with some mixed results...

Before some much needed technical input was acquired by Suzuki’s R&D race shop, things hadn’t always gone according to plan. Despite the Hamamatsu factory’s best efforts their early smaller capacity race bikes were found to be lacking.

One of the firm’s earliest 125s designed to seriously compete outside of Japan was the RT60. Designed by Takeharu Okano for the 1960 race season, it was a relatively conservative air-cooled two-stroke twin running simple piston porting. Suzuki had by then grasped that revs meant power so had opted for an over square engine bore and stroke of 44 x 41mm. This delivered around 13bhp at 11,000rpm. At 82 kilos the bike wasn’t the lightest in the class and with short, dumpy expansion chambers it was apparent that Suzuki still had some way to go in terms of delivering an effective lightweight racer.

The bike appeared on the Isle of Man that year as the Colleda RT60, despite being entered by the Suzuki factory team. The Colleda name had been taken from a successful domestic commuter machine and translated as ‘this is it’… which unfortunately it wasn’t! The best the Colledas could manage was a 71.88mph lap with a race time of 1.34.296. Carlo Ubbiali lapped at 85.61mph and his winning time was 1.19.212 on his all-conquering MV Agusta. The RT60’s biggest issue was that it remained down on power even when the factory carried out modifications. At best it could deliver 13bhp, which left it with a massive deficit when compared to the like of Honda, MV Agusta or MZ which were consistently and reliably making 7bhp more. Even when pushed to a phenomenal 16,000 revs the team couldn’t get the power needed to run with the pack despite the benefit of running chromed bores which should, in theory at least, have released more power. The lack of success wasn’t for the want of trying or expert input; legendary racer Geoff Duke had ridden an RT60 back in the Japan and had reported back favourably. The great man had even gone so far as to supply written notes on the circuit along with his expertise as a racer. Despite all this and more the bikes still fouled plugs, thanks to a very oily 8:1 petrol-to-oil mix, so it was a case of back to the drawing board if Suzuki was to stand any chance of successfully competing at international level.

The following year Suzuki upgraded the RT60 by virtue of a pair of rotary disc valves which, allied to larger carburettors, got the power of the subsequent RT61 up to 15bhp, but it was still not sufficient. In a frantic attempt to keep up with the front runners, riders found themselves over-revving the new twin, which was willing, but not reliable. The issue was found to be the ignition system, which had a proliferation of gears very accurately cut to prevent backlash that subsequently overheated, which then caused the magneto’s bearings to run dangerously hot. 1962 saw the company carry out a massive change to their 125 GP racer. The bike became a disc valve single with 54 x 54mm engine that delivered an astounding

Here's factory Suzuki rider Hugh Anderson (no.42) going head-to-head with Ken Martin (no.94) on his 125cc Bultaco at Cadwell Park in September, 1962. The following season the Kiwi racer won both the 50cc and 125cc World Championships with Suzuki.

24bhp at 11,000rpm; equipped with seven gears the all-new machine could now reliably brake the 100mph barrier. How did this happen?

Suzuki’s fortunes had changed almost overnight when Ernst Degner brought with him most of MZ’s secrets. The new RT was almost a copy of MZ’s RE125 and the introduction of a rear-facing exhaust (as per the East German machine) helped to reduce the front profile of the bike. Suzuki were on the up, but there

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was still much to learn. Even their newest employee was about to be mightily impressed with the resources available to an aspirant world championship Japanese factory!

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