UNDERPOWERED BUT RELIABLE

The Crux S carries forward the Yamaha 106cc single-cylinder, four-stroke and air-cooled engine from its predecessor, only adding on a few bits and pieces to achieve cleaner breath and conform to new and stringent emission norms that came into effect in April 2005.
Bore and stroke for the cast iron cylinder are undersquare at 49mm and 56mm, while the alloy head uses twin valves. The camshaft is chain-driven with a tensioning system visibly protruding from the rear of the block. A standard slide-type carburettor does duty and power and torque figures are 7.3bhp at 7500rpm and 0.76kgm available at 6000rpm.
There's no option of a self-start for this bike and we found the Crux S isn't happy about being woken up each morning as it requires liberal use of the choke on every cold start on even a warm summer morning. Yet, once up and past this stage, the Crux S delights with a silken smoothness and light clutch feel that make for a good riding experience.
The motor is completely vibe- and buzz-free and utilises a four-speed gearbox, which is as fine as the best on any motorcycle in India. Gearshifts are via a heel-and-toe shifter, in our favourite one-down and three-up pattern and all ratios are accurately spaced to make the best of riding in the city. The long-stroke nature of the engine with its strong low-end torque means gearshifts are kept to a minimum, with this Yamaha engine further endearing itself in being capable of pulling away in top gear from as low as 20kph without a hiccup.
Acceleration is just as brisk as any other similar 100cc machine in India, with 60kph going by in a creditable 7.54 seconds, the Yam pulling on to a top whack of 93kph.