Showa SSF fork and engine upgrades for Suzuki’s RM-Z450 and 250

WORDS: Kevin Hipp
PHOTOS: Suzuki

Suzuki has announced the 2013 RM-Z line to the public, and the updated bikes received some features that are sure to interest the motocross community. The big changes come to the new RM-Z450 and RM-Z250 models, which receive a new fork, engine and transmission tweaks and an optional FI indicator to help track operating time for better management of maintenance intervals.

Showa’s new Separate Function front Fork (SSF) now resides on the 2013 RM-Z450 bringing lighter weight and better performance to the 249 pound machine. This SSF separates the spring and damping functions of the fork into the separate fork legs, with the right leg housing the spring and the left leg containing the damping circuitry.

[A new piston is 13 percent light yet just as strong, and the piston pin has been given a surface treatment to reduce friction. The intake cam timing and lift have been modified for smoother power delivery. The 450’s five-speed transmission has been altered to improve shifting. This was achieved by reshaping the shift cam, stopper spring, and the drive shaft.

[The muffler has seen some changes to increase low to midrange power without effecting top end. The muffler cap now uses bolts instead of rivets, simplifying the task of changing muffler packing.

Suzuki introduced the coupler system back on the 2011 models and has kept it for 2013. The system consists of three plug-and-play couplers that alter the fuel delivery settings – one for normal, one for lean, and another for a richer setting to tune throttle response and power delivery to suit conditions.

A new high power ignition coil along with a higher performing ECM provides better combustion efficiency. This resulted in an increase in roll-on performance.

Using the optional FI indicator (part no. 36380-28H00), riders can now track engine-operating time and better manage maintenance intervals.

Slight chassis refinements to the frame and seat rail bring better balance and stability.

The RX-Z250 shares many of the same new features as the 450. The piston on the 235 lb. machine has been redesigned, dropping the weight by three percent without any compromise in strength. Like the 450, a new ECM and a high output coil have been added to this year’s 250 model. A redesigned exhaust system conforms to new FIM sound regulations while increasing mid-to-high rpm power. New Dunlop MX51 series front and rear tires help put that power to good use.

The cooling system on the quarter-liter bike has been revamped with a redesigned radiator fin and revised water hose routing increasing cooling efficiency. A new by-pass hose has been added to help simplify cooling system maintenance.

The two-stroke RM85 and RM85L have not seen any changes for 2013.

The MSRP for all 2013 RM/RM-Z models have not been announced yet.