CRF450R - Honda's sand shark
DIRT MONSTER: The CRF450R has constantly evolved, responding to competition and riders’ needs in equal measure.
CAPE TOWN - Any new CRF450Rhas to be fully proven, in race conditions. Knowledge acquired by Honda in the All-Japan Motocross Championship, was constantly fed back into development of the production bike.
For 2013, the CRF450R uses the sixth generation aluminium twin-beam frame, which has been built from the ground up retaining a focus on mass centralisation. It also features rigidity levels tuned in certain key areas to improve rider feel when landing from jumps, with revised geometry for increased front and rear traction, and turning ability.
The use of KYB air-sprung front forks, offers significant weight savings with improved performance and versatility in varied track conditions. A compact KYB rear shock sits lower in the frame and operates via Honda’s Pro-Link system with a brand new aluminium swingarm.
The CRF450R’s PGM-FI fuel-injected, 449cc single-cylinder engine has been re-tuned for major gains in the low and mid-range torque area – with no loss of top-end power – plus a refined connection between throttle and rear tyre. The lighter clutch is easier to use. Short, dual mufflers contribute to mass centralization, improved low/mid power delivery and provide a slimmer side profile.
The CRF450R’s 9.35kg aluminium twin-beam frame is completely new, and was designed from the outset to facilitate mass centralization and a low centre of gravity.
A KYB air-suspension USD front fork, removes 800g of weight due to the lack of conventional coil springs. The unsprung weight of the fork lowers and front wheel is also reduced.
The preload can be changed via the Schrader air valve fitted on the top of the fork cap, doing away with the need to change spring sets. Air alone fulfils the pressurisation needs; there’s no need for nitrogen or other inert gasses. The fork and shock are also fully adjustable for compression and rebound damping.
An additional benefit of the KYB air suspension fork is that the CRF450R can be strapped down for transport simply by removing air pressure, lowering the front end with no risk of damaging fork seals.
The CRF450R’s bodywork inherits the ‘triangle proportion’ that has long set the CRF family of competition machines apart. Another phrase used by Honda’s engineers during development was ‘man maximum, mechanical minimum’.
In support of this the radiator shrouds, side covers, seat and fuel tank offer a slim, smooth and continuous transition allowing the rider a great deal of freedom and flexibility of movement. The bodywork attachment points where the rider contacts the bike have been made more rigid so the rider can grip the bike more solidly, for better feel and control.
The front disc cover has been redesigned for improved protection and is now in two parts for easier maintenance of the 240mm wave-pattern disc and twin-piston brake caliper. The rear brake is a 240mm wave-pattern disc with single-piston caliper. Both calipers use sintered brake pads. Lightweight aluminium rims, with a directly attached spoke pattern layout reduce unsprung weight; front wheel size is 21 x 1.6in and 80/100-21 tyre, the rear is 19 x 2.5in and 110-90/19 tyre.
Optimising the liquid-cooled, four-valve Unicam engine’s efficiency started with improved gas flow rate through the cylinder head; refined inlet port shapes provide 3% more flow, and revised valve timing, with more overlap, maintains maximum power at high rpm, while increasing low and mid-range output.
The compression ratio has also been raised, from 12.0:1 to 12.5:1. The result is an engine that delivers 10% more torque low down, with a linear torque curve plus stronger mid-range power and no loss at the top-end.
For increased durability the piston oil jets uses two holes instead of one, for improved cooling of the piston’s underside.
See the vehicle specifications here
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