Yamaha seems to be coming into its own. The just launched R-15 is the first bike in India to have four valves and is water cooled, not air cooled. These are two exclusive features which no other bike in India has. In addition it has other rare techno upgrades like electronic fuel injection, disc brakes both front and rear, and six speed transmission, which only the old RD350 had.

Its power plant is a 149.8 cc, 4-stroke single cylinder, single overhead camshaft unit, having bore X stroke of 57 mm X 58.7 mm operating at a compression ratio of 10.4 which produces 17 PS (==16.77 bhp==12.5 kw) at 8500 rpm. As mentioned above, fuel injection into the cylinder is activated by a 26 pin Electronic Control Unit and is sprayed in by a six-hole injector. There is no carburetor. The engine develops a torque of 15 Nm at 7500 rpm. Ignition is transistor controlled. Electrics are 12 volt and headlight power is 35 watts. It has twin-headlights, which makes it very attractive to look at but not very effective to look (at the road) from. This is because the brightness produced by TWO bulbs being supplied thru a 35 watt cable is NOT as bright as a single bulb alone being supplied 35 watts. To understand this, just imagine: it is like one man marrying TWO nine-year old girls instead of ONE eighteen year old girl !

The delta-box frame has the engine as a stressed member and rides on thin 80/90 X 17 tire front, and slightly fatter 100/80 X 17 tire rear. Stopping power is provided by disc brakes both front and rear. Wheelbase is a short 1290 mm with 160 mm ground clearance. Dry weight of the bike is 120 kg while kerb weight is 131 kg. The return type six speed gearbox operates thru a constant mesh wet multi-plate clutch. Lubrication is wet-sump and engine oil capacity is ONE liter. Fuel tank capacity is 12 liters. Front suspension is twin fork while rear is mono-shock. Starting is only by elektrik self-start, there is no kicker.

Technical-Comment: The HH Karizma (kerb weight 150 kg) also produces 17 PS of power, same as this R-15, but Karizma produces 17 PS at 7000 rpm while R-15 does it at 8500 rpm. Of course there are a lot of bikes that revv upto 8500 rpm, such as HH Xtreme and Hunk, TVS Apache150 and TVS RTR 160. Squeezing out 17 PS from the R-15 engine which is 70 cc smaller than HH Karizma engine by making the R-15 revv 1500 rpm more than Karizma and the R-15 (kerb weight 131 kg) weighing 19 kg less than karizma boosts the power to weight ratio of the R-15. Power-to-weight ratio of Karizma is 113.34 bhp per tonne, while power-to-weight ratio of R-15 is 129.77 bhp per tonne. Thus power-to-weight ratio of R-15 is 14.5% higher than Karizma, which is quite a lot. Yet there is a downside. The engine life factor (ELF) of R-15 is 1.131, while ELF of Karizma is 1.587. Thus the Relative Life Expectancy of Karizma is more than 40% longer than R-15. Thus if R-15 lasts for FiVE years, then under the same conditions, Karizma will last for SEVEN years, given that the quality of materials used in Karizma and R-15 is exactly same, which is a fair assumption bcoz both Yamaha and Hero Honda are equally recognized for quality.