The new 2-stage valve control system, called 'V4 VTEC', is chain driven and aims to provide more torque through the lower and middle ranges by only utilising two valves in each cylinder until just over 7,000 rpm when the other two valves per cylinder also kick in to play. The bike responds with a distinct change in engine note and intake roar as all four valves come on song. Lower down in the rev ranges my seat of the pants felt only the slightest of improvements over the earlier non 'VTEC' model, but power seems a little stronger up top than before with a generous amount of over-rev.

The new engine is noticeably quieter than the previous model.  Gone is the characteristic whine from the gear driven cams in the 781cc V-Four engine.  This is mainly due to the move to chain drive for the cams but also the reduction in noise from only having two valves per cylinder operating most of the time rather than four.  The ultra smooth six-speed gearbox complements the sophisticated fuel-injected engine and the two work seamlessly together to provide reasonably strong drive at any road speed.

The gearbox ratios have also been changed.  First, second and third gears are now closer together and combine with a one-tooth smaller front sprocket to deliver sharper acceleration.  To reduce the shocks of upshifts to the drive train the clutch's 2-step coil spring damper was replaced with a new 3-step damper that ensures smoother, more comfortable operation in virtually all traffic and riding conditions.

The new VTEC system features a set of compact, hydraulically actuated lifter sleeves installed inside the inverted buckets of the valve train's direct-actuation valve lifters, over one intake valve and one exhaust valve in each cylinder. During low-to-midrange operation, the lifter sleeves slide benignly up and down over the tops of the valve stems, allowing only two valves in each cylinder to open.

At around 7,000 rpm a burst of oil pressure to the lifter sleeves forces their spring-loaded engagement pins to slide across the centre hole and initiate actuation of the remaining two valves of each cylinder. The engine suddenly comes on cam, full 4-valve operation kicks in.  The transition is remarkably smooth but it still can be felt and a little care is needed on very slippery surfaces.

The VFR's excellent PGM-FI fuel injection system has also been upgraded with a set of new 12-hole injectors replacing the one-hole injectors currently used to realise finer fuel atomisation.  Combustion efficiency is also aided by new, hot-firing iridium spark plugs, which are ignited by compact, new, high-energy 'coil-on-plug' spark plug caps (like those used on the CBR600).