Suzuki has released technical details of its 2019 RM-Z250. Updates include new styling sitting atop a new frame, swingarm and suspension, plus a more powerful and torquey engine and updated Suzuki Holeshot Assist Control and traction management systems.
Focus on the engine – 2019 engine changes in a nutshell:
A newly-designed cylinder head, intake and exhaust ports which increase airflow and combustion efficiency for more power.
A new intake cam profile and increased valve lift also increases power and controllability, improving throttle response across the revs.
New cam chain tensioner and adjuster tuning, plus new cam chain tensioner material to help reduce mechanical loss.
30% larger air filter aperture and straighter outlet tube from the airbox increases power at all engine speeds.
High rpm power boosted by new twin injector (was single injector). The main injector is still in the throttle body, new secondary injector is nearer the airbox, giving the fuel and intake air more time to mix prior to combustion, improving efficiency.
Repositioning of the main injector means fuel is injected upwards to hit the butterfly valve directly, improving atomisation of the fuel, combustion efficiency and throttle response.
Improved throttle response is further aided by a 17% increase in fuel pressure and an updated throttle body.
New the gear ratios improve rider feeling and throttle connection. Second gear is changed to a higher ratio, going from 30/17 on the previous model to 29/17. Final ratio is also changed, from 49/13 to 50/13
A 99mm longer exhaust has a new structure and internal material boosting power across the revs, but mostly at lower engine speeds.
Chassis changes in a nutshell:
A new frame retains fore-aft rigidity along the length of the bike but increases torsional rigidity by 10%.
Overall weight reduced by 370g.
A new manufacturing process of the swingarm shifts from a swaging process, hydroforming, removing the need for welding and saving 80g. It also uses a tapered cross section for improved rigidity, plus a new chain guide saves another 30g and is more durable.
New hexagonal seat rails are more rigid and make maintenance easier, with removal of the air filter simpler than before
New, more rigid, engine mounts are 8.5mm higher for better handling. Mount brackets switch from steel to aluminium, saving 90g.
Ergonomic changes help improve handling performance and the bike’s agility.
New Renthal handlebars are straighter for more freedom of rider movement. They’re 7.4mm further forward and 3.8mm lower, while the footrests are 3.3mm forward and 5.2mm higher adjusting the riding position subtly.
A new fuel tank saves 312g, while a slimmer seat loses another 274g and also makes it easier for the rider to move around.
KYB sprung forks for 2019
Fully-adjustable KYB suspension runs spring forks replacing the air forks on the previous generation, and a new rear shock. There are also further weight reductions, thanks to a lightweight spring with thin wire diameter, derived from MotoGP know-how (they say but don’t explain). Anyway, weight drops by 370g, while the rear suspension linkage is 15g lighter.
A larger front brake disc (250mm to 270mm. New brake pads give a more linear feel and a new rear brake master cylinder improves operation, better prevents dirt entering the system and keeps out the way of your right boot more.
Handling is improved with lighter rims – front 40g and 60g rear. Dunlop’s new MX33 tyres are standard.
Suzuki’s advanced Holeshot Assist Control (S-HAC) and traction management systems are improved for 2019.
S-HAC helps you get out of the gate, adjusting ignition timing to help the launch with two modes mode-A for softer conditions or mode-B for grippier conditions (advance or retard ignition timing).
In both modes, S-HAC deactivates and ignition returned to normal timing after six seconds, when the rider shifts in fourth gear, or when the throttle is closed.
Updates to S-HAC make it easier to control engine speed before and during the launch and improve controllability accelerating towards the first corner.
Once out of the gate and racing, Suzuki’s traction management system helps the new RM-Z250 maintain an edge as the bike’s ECU monitors throttle position, engine speed and gear position to control ignition timing and fuel injection rate to control engine output.
The system differs from road-based traction control in that it does not monitor rear wheel spin. It does not control traction once the tyre slips. Instead, it offers constant control that maximises traction the whole time it is functioning.
First introduced on the RM-Z450 in 2008, the system has been continuously honed and refined across Suzuki’s motocross range, with new ECUs promoting faster processing, as well as other new components including throttle bodies and updated intake systems enhancing performance.
For 2019 more ECU updates and the adoption of twin injectors further improve the system’s operation.
Availability: The 2019 RM-Z250 will be available from authorised Suzuki dealerships in spring 2019, with pricing to be announced.
More information at your national Suzuki website or visit: suzukicycles.com
Jon PearsonEnduro21 Editor and Bike Testerjon.firstname.lastname@example.org