Smaller faster and lighter for CBR600RR

Honda acknowledges that the market has overtaken the old model, which is still no slouch, and that it had to do something major to get back into the game. The designers claim that literally every part was examined during the redesign, often with an eye to see where weight savings could be made.

Below you'll find the factory's summary of what it's done to the engine and chassis.

Engine
Not only are the new engine's front-to-rear and top-to-bottom dimensions by far the smallest in its own 600cc class, its front-to-rear length is also smaller and more compact than any inline-4 engine in the 250cc class as well.

This new engine's smaller dimensions were achieved through a total rethinking and, among other changes, repositioning of the engine's main shafts within the crankcase in a tight triangulated configuration that narrows the crankshaft-to- countershaft distance by over 30mm. Combined with detailed changes elsewhere in its design, these closer dimensions make possible a drastic reduction in crankcase size and, by extension, weight. The crankcase castings alone weigh over 900g less than its predecessor, representing the largest part of the engine's exceptional 2kg reduction in weight compared to the current model.

Other modifications to reduce engine weight include a new magnesium head cover (330g lighter), new nutless connecting rods, new single exhaust valve springs matched to smaller and lighter lifters, a smaller new neodium ACG magnet and many more detailed changes that all add up to the realisation of the new engine's astoundingly smaller configuration and lighter weight.

Stronger Performance
Many of the new technologies and improvements made were developed and tested on the CBR1000RR Fireblade and adapted to the new engine, including modified intake and exhaust ports and changes to the intakes velocity stack lengths and taper, and to the ECU programming governing the control of its two-stage PGM-DSFI fuel injection system. The CBR's lighter weight new stainless steel exhaust system also features new in-line exhaust valve to control exhaust pressure for maximised performance.

Resulting performance is not only stronger throughout the engine's wide powerband, but also smoother and more linear for more easily accessible and widely enjoyable top performance. The new engine also features a noticeably stronger pull of torque between 7,000 and 10,000 that not only experts, but all riders can better take advantage of for more exciting winding road riding.

Likewise, for those times when a greater range of acceleration is needed, such as on the racetrack, the engine's power peak has also been extended 500rpm compared to the current model.

Improved PGM-DSFI Dual Sequential Fuel Injection System
Amply supplied with large volumes of cool, dense air by its new nose-mounted ram air intake duct, the new CBR600RR uses essentially the same two-stage PGM- DSFI fuel injection system as before to ensure optimal fuel atomisation and cylinder charging at all engine speeds. One set of injectors installed at the entrance to the intake ports provides an ideal air/fuel mixture for quick starts and strong, smooth low-to- midrange acceleration. At higher engine speeds, when both the throttle and ram air intake are opened wide, the system's second set of injectors installed in the roof of the aircleaner kick in to deliver a minutely timed jet of fuel that cools the high-volume air intake to create a denser mixture that improves volumetric cylinder filling efficiency for stronger acceleration.

New Pistons and Connecting Rods
The CBR's lightweight forged aluminium pistons are treated with a molybdenum shot process that impregnates the surfaces of the piston skirts with durable, low-friction molybdenum such as used on the pistons installed in the CBR1000RR Fireblade.

Featuring a thinner lower oil ring for further reduced friction, the pistons are also cooled from underneath by new high-pressure oil jets built into the crankcase, which provide a stream of oil to the undersides of the pistons that effectively wicks away heat build-up.

Also featured on the Fireblade, lighter new nutless connecting rods use standard threaded bolts screwed directly into tapped holes in the rods to hold their endcaps in place. This makes an important contribution to the engine's greatly reduced reciprocating weight, and combines with the pistons' minimised friction to realise more instantly responsive power and quicker acceleration.

New Knock Sensor
The new CBR600RR's engine has also been equipped with a knock sensor that maintains optimum spark advance during mid-to-high speed operation while constantly monitoring combustion performance for any signs of detonation. Should the knocking of detonation be detected, the system automatically retards the spark advance just enough to eliminate the problem. Specially programmed to distinguish the sound of detonation from other engine noises, this system can even correct for the use of low- octane fuel, instantly retarding timing until any signs of detonation or knock disappear, and then gradually advancing the timing again to a point just short of the knock zone to maintain optimal combustion characteristics at all engine speeds.

New Low-Lash Transmission
The CBR's new transmission also takes full advantage of the engine's performance characteristics for stronger acceleration while complementing the engine's reduced torque reaction to greatly reduces the amount of gear lash felt during transitions between acceleration and deceleration.

This new transmission also features new reverse- taper shift dogs that contribute more positive gear shifts in racing applications and help realise much smoother and more instantly responsive riding experience than that found on virtually any other machine in the new CBR's class.

The Heart of the Matter - Reduced Engine Size
As noted above, the new CBR600RR's engine features exceptionally compact dimensions which permit more effective positioning within the frame for optimised mass centralisation and improved handling. Its smaller fore-to-aft length also made it possible to shorten the CBR's wheelbase by a remarkable 20mm (from 1,395 to 1,375mm) while simultaneously gaining an extra 5mm in swingarm length (to 573mm) and extending the steering head by 13mm, as measured from the crankshaft. The chassis' shorter wheelbase combines with the extended steering head, which increases leverage on the vehicle's rotating axes, to realise sharper, more responsive handling for more aggressive control on winding roads and circuit corners, yet still remain confidently reassuring for riders of not fully expert skill levels.

To complement the effective 15mm rearward repositioning of the engine's centre of gravity, the rider's seating position was also shifted back 15mm to achieve even lighter, more responsive manoeuvrability and handling control. The machine's overall centre of gravity was also raised by 3mm over the current model to achieve more neutral response to rider inputs, easier side-to-side flickability and smoother handling.

Race-Ready Suspension Components
Handling is overseen by the same impressive 41mm inverted HMAS cartridge-type front fork, which provides smoothly responsive performance coupled with excellent rigidity and low unsprung weight for the precise and confident control that world-class racing demands.

Integrated into the CBR's rigid but lightweight swingarm is essentially the same Unit Pro-Link rear suspension system pioneered on the race-winning RC211V MotoGP racer. Its highly advanced design completely isolates the frame from the shocks and stresses generated by conventional rear suspension systems, especially under aggressive riding and racing conditions.

Wheels and Brakes
Another factor that plays an important role in achieving the lighter weight and more centralised mass required of such a high-performance road and track machine are the CBR's triple-spoke cast aluminium wheels, which feature compact hubs for an ultra- lightweight design that also minimises unsprung weight. Like its predecessor, the front wheel is stopped by a high-performance pair of radial-mount brake callipers like those featured on both the CBR1000RR and the RC211V MotoGP racer.