Darting associated with the original Rush isn't completely gone, however. Even after testing the new 2011 Rush Pro-R, my concern about front-end stability hasn't changed. This machine still requires special attention from the rider when it's time to slow down or tackle a steep descent.

Sending power to the ground is the excellent Ripsaw track with 1.25'' studs – arguably the best performance track around. (Photo: Pascal Bastien/Moto123.com)

A bit of fine-tuning
The rider has to take time to properly set the suspension at all three points in order to create the desired weight transfers and make the Rush bend to his or her will. Only make one change at a time, though. Then, go out and see how the sled behaves. It's also easy to improve front-end handling by fitting a pair of Cobra Head plates from Qualipièces, which eliminate much of the darting by levelling snow before it touches the carbide runners.

Sending power to the ground is the excellent Ripsaw track with 1.25'' studs – arguably the best performance track around. Traction is never a problem even when fluffy snow covers the ice. Accelerations remain linear both on flats and inclines. What's more, the Rush Pro-R gets a lighter, flower-shaped, cross-drilled rotor that provides flawless braking power and precision.

Competent albeit smelly engine
The 600 Rush Pro-R gets the latest Cleanfire2 engine – a 600-cc, 2-stroke, twin-cylinder that produces an impressive 120 horsepower. Introduced on the IQ models, this little marvel of smoothness now benefits from advanced fuel injection technology to allow strong accelerations on par with the best 2-stroke powerplants in the industry. It's not the cleanest, however. While the engine meets EPA emission standards, it generates more oily smells than competitors.

The superior dynamics of the Pro-Ride chassis (compared with the previous architecture) essentially turn them into thrill-inducing machines. (Photo: Pascal Bastien/Moto123.com)