We are big fans of MotoGP here at Faster and Faster, and you see MotoGP-related posts here very often. But talk about 125cc motorcycle GP racing, and with us, you draw a blank. We admit we don’t follow 125cc racing, and we hardly know anything at all about those bikes and the men who race them.
But are we missing something? We thought it would be interesting to take a quick look at a 125cc racebike’s specs and see how, as a package, one of these machines would stack up to a modern-day 1000cc road-going superbike. Let’s take the KTM 125 racer, for example. The bike is powered by a single-cylinder, liquid-cooled, two-stroke 125cc engine that makes 55 horsepower at 13,000rpm, and 31Nm of torque at 12,800rpm. No fuel injection here – the bike uses a Keihin carburetor.
The minimum weight limit (bike+rider) in the 125cc class is 136kg, so the KTM 125 racer probably weighs just 80 kilos! The twin-spar chassis is made of aluminium, suspension is Öhlins front and rear, brakes are by Brembo, wheels are lightweight Marchesini units and the gearbox is a six-speed unit. Fuel capacity is 13 litres, which means the bike probably averages about 10 – 11km/l during races.
On to, say, a Suzuki GSX-R1000 now. The engine is a 999cc, four-stroke, liquid-cooled inline-four, and depending on who you talk to (or which motorcycle mag roadtest you choose to believe), it makes anywhere between 165 – 180 horsepower at 12,000rpm. Top speed is close to 300km/h, and while we don’t really know the exact top speed of the KTM 125, we don’t suppose it would be more than 220km/h. The Suzuki’s 1:1 power-to-weight ratio also compares favourably with the KTM’s 1:1.45.
The GSX-R1000 is about twice as heavy as the KTM 125, but also packs three times the power. So the numbers at least are weighted in favour of litre-class superbikes. How would things be in the real world? Would an average rider who weighs 85 kilos, riding a GSX-R1000, be able to keep up with a 55kg professional racer, on a 125cc GP racebike, on a set of mountain twisties?
Would the 125’s agility and higher corner speeds (?) offset the Gixxer’s sheer power, acceleration and higher top speeds? What if the GSX-R was fitted with high-spec street rubber, while the KTM ran racing slicks? We'd love to find out, but for that, we'll need a KTM 125 racer and a 2007 Suzuki GSX-R1000. Anyone willing to lend us these two machines for a day…? :-D
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