Thread: Yamaha YZF-R15-Engine,Gearbox And Performance

The YZF-Rl5's four-stroke engine brisdes with more technology than has ever come together on an Indian motorcycle. This 149.8cc, four-valve unit breaks the mould to offer liquid-cooling, a technology ideal for India with its blazing summers. Fuel injection feeds its sleeve-less DiASil (Die-cast Aluminium-Silicon) cylindermating 20 percent silicon and aluminium alloy-with Yamaha claiming 60 percent improved cooling over a conventional cylinder. The DiASil cylinder cannot be re-bored, although this breakthrough cuts manufacturing costs by 30 percent.

The R15 uses a hemispherical-shaped combustion chamber with its spark plug centrally located for an even flame spread. This Yamaha uses a forged piston that is well suited to the extreme temperatures and high rpm routinely achieved by performance bikes. And the YZF-R15 offers a six-speed, close-ratio gearbox that shifts with Rolex-like precision and works in unison with a perfectly weighted clutch.



The YZF - Rl5 motor sounds as potent as expected of a single cylinder, 17bhp (on tap at 8500rpm) bike. It is surprisingly not as audibly smQath as expected of a liquid-cooled motorcycle, yet willingly revs vibe-free even when pushing engine revs close to its redline. The Rl5 displays thoroughbred sports bike character, with its power delivery relatively flat below 7000rpm, after which the Rl5 lights up with Diwali gusto to gun past its 1.52kgm at 7500rpm torque crest. As with most performance bikes, one has to pull out the whip and work those six speeds, keeping the R15 on the boil in order to extract optimum performance.

Our tests found the R15 with its 129.7bhp per tonne power-to¬weight ratio effordessly faster than the 223cc Hero Honda Karizma R, yet the refined Karizma isn't the fastest sportsbike in its class. The R15 cannot match a Bajaj Pulsar 220 DTS-Fi when accelerating, and although it's easily quicker than the 1VS RTR 160 FI at higher speed going past 100kph in 14.14secs, the RTR 160 FI, and even a carbureted RTR 160 will keep up with the R15 that zips past 60kph in 5.02 seconds. Keeping the R15's performance bike positioning and premium pricing in mind, we can't help but wish it packed a few more horses. The R15 musters a true maximum speed of124kph on a flat stretch of tarmac and its tall sixth gear ensures a laidback cruising ability in the vicinity of100kph.