2015 Honda CRF450R

Honda has released details on its 2015 CRF450R, with the four-stroke motocrosser receiving plenty of love and attention for the new model year. Enhancements have been made to both the engine and chassis, while new radiators boost engine cooling.

There’s increased power and torque off the bottom and more output at the top. Peak power is up .just over 1hp to 53.7 at 9000rpm with maximum torque of 48Nm arriving at 7000rpm.

The redesigned four-valve Unicam cylinder head and exhaust are chiefly responsible for the gains. The head is built to the specifications raced by HRC throughout the 2014 season, and features exhaust ports that exit to the right, rather than left.

There’s now shorter exhaust pipe that no longer travels around the frame, reducing length by 320mm. The twin exhaust mufflers also feature a larger internal diameter. PGM-FI Dual fuel injection has been revised to match the engine’s increased efficiency. There are also upgrades for the transmission, piston and crankcases to improve long-term durability.

The engine now features three-way mode selection: mode one delivers the standard combination of ECU maps, mode two serves up silky-smooth throttle control, and mode three returns aggressive, all-out response and power. A highly visible LED built into the lightweight button signals the map in use with a quick press and number of subsequent flashes. If a new map is selected the choice is also confirmed to the rider.

The internal architecture of the engine remains unchanged: bore and stroke is set at 96mm x 62.1mm, with 36mm inlet valves and 31mm exhaust valves. Compression ratio is 12.5:1 but the 46mm throttle body employs a revised throttle return spring giving a much lighter – and less fatiguing – action.

The left crankcase material is thicker around the crankshaft bearing and pivot point. To cope with the increase in power the piston now shares the CRF250R’s heat treatment process.

Every gear except first is now manufactured from Nickel Chrome Molybdenum. Developed by Honda in other areas of manufacture, it is claimed to be 10 per cent stronger than the Steel Chrome Molybdenum (SCM) material it replaces¬, with no weight penalty. An extra 20g has been added to the ACG flywheel and the 4.5 per cent increase in inertia – from 7.75kg/cm2 to 8.1kg/cm2 – improves engine torque feeling.

With the revised exhaust routing the radiator core sizes have been reversed left and right, with the larger radiator on the left. Pitch area between the fins has been narrowed, from 3.75 to 3.5mm creating a denser structure with increased surface area for improved cooling efficiency.

The 48mm KYB Pneumatic Spring Forks (PSF) units have now moved on to the next level (PSF2) and receive redesigned, lighter internals plus approximately 10 per cent friction reduction. High and low-speed rebound damping adjustment joins the other adjusters on the fork tops, while the rear shock’s adjusters have also been rationalised together.

Up front, a redesigned 260mm disc replaces the previous 240mm item, while the aluminium twin-beam frame, swingarm and Pro-Link rear suspension linkage remain unchanged. A new graphics package and Dunlop MX52 tyres round out the 2015 CRF450R’s suite of upgrades.

Meanwhile, highlights of the CRF250R include:

Local price and availability for both models are yet to be announced.