2018 Suzuki RM-Z450

Suzuki's the latest manufacturer to unveil an updated 450cc motocrosser, with the company calling the 2018 RM-Z450 its "hardest-hitting, sharpest-handling, best-balanced and most rider-friendly production motocrosser" in its history.

The redesigned 2018 RM-Z450 engine has more low-end torque, a flatter overall torque curve, and more peak power.

The engine now has enhanced airflow, while the outlet tube leading from the airbox to the throttle body is also straighter, which Suzuki says reduces intake resistance for increased power across the rev range.

The throttle body is likewise revised, providing a "more uniform fuel-air mixture to further increase power while providing a smoother throttle feel". The elimination of a throttle linkage is claimed to improve throttle feel even more.

The fuel-injector spray path now aims fuel upward to hit the throttle butterfly valve directly for improved atomisation. Inside the intake port, the shape is updated for improved tumble flow of the charge as it enters the cylinder, boosting power at all engine speeds.

The intake-port shape is matched to a new high-lift intake-cam profile, while inside the combustion chamber a new piston-rib design adds strength and durability to match the engine’s higher output. There's an updated muffler, too.

To maximise traction, the engine control module automatically adjusts ignition timing and fuel injection based on throttle position, engine speed and gear position. The third-generation traction system has a revised ECU with both faster processing and more memory than previous versions.

Holeshot assist
An integral part of the 2018 RM-Z450’s electronics package is holeshot assist, with the updated three-stage system assessing throttle position and gear selection and then adjusting ignition timing to optimise engine output for faster launches.

The system returns the ignition timing to normal operation six seconds after launch, when the rider shifts into fifth gear, or when the throttle is closed.

The holeshot assist gives riders a choice of three settings which can be quickly selected via a handlebar-mounted switch. The “A” mode is programmed for hard surfaces, and the “B” mode is for normal dirt conditions. Riders can also select the “Off” setting to retain standard ignition timing.

Chassis updates
The 2018 Suzuki RM-Z450 has an all-new light-weight frame and swingarm. The head pipe point has been relocated 10mm back, resulting in a shorter 1480mm wheelbase, while the weight distribution has been brought forward for increased agility and stability.

Frame advancements include a more rectangular cross-section for the main spars, improved fore-aft rigidity and optimised overall rigidity, together with a 700g weight reduction.

Swingarm upgrades include thinner materials for a 100g weight reduction and optimised rigidity, which translates to increase cornering and stability. Additional chassis upgrades include new seat rails with hexagonal tubing for slimmer dimensions and better rigidity.

The revised seat-rail shape also allows more airbox capacity and easier air-cleaner service access, while allowing room for the RM-Z450’s new Showa Balance Free Rear Cushion shock.

In the cockpit, a new straighter bend for the Renthal Fatbar aluminium handlebar helps riders shift their weight forward for improved cornering. And finally, a lighter chain guide provides more even contact and higher durability, while an engine protector guard shields the water pump and magneto cover from potential damage.

There's new Showa front and rear suspension. Up front, an updated 49mm Showa coil-spring fork based on works A-type design replaces the SFF-Air fork of the previous-generation RM-Z450.

While out back, a new Showa Balance Free Rear Cushion (BFRC) shock has been fitted – the first time on a production motocrosser as standard equipment. The design balances pressure above and below the piston to better control the stroke and smooth out reactions to bumps and chop, even under severe braking.

Lighter wheel rims and new Bridgestone Battlecross X30 tyres are fitted, while a larger 270mm wave disc up-front improves stopping performance.

Riders can adjust the engine performance to suit varied track conditions. By plugging in either of two additional fuel-setting couplers, richer-than-stock or leaner-than-stock fuel selections can be made.

The bike has “Beak DNA,”, while the styling refresh also extends to the seat shape, which makes moving between seated and standing positions easier.

The 2018 RM-Z450 is expected to arrive in Australia in spring 2017, with final specifications and pricing being confirmed closer to launch.