31Engine:With a focus on improving both power and manageability, the 2019 RM-Z250’s engine has undergone significant enhancements.• Peak power is improved with a newly-designed cylinder head and new intake and exhaust ports which increase airflow and combustion efficiency.• A new intake cam profile and increased valve lift also increases power as well as controllability, giving an improved throttle response across the rev range.• There’s also a change to the cam chain tensioner and adjuster tuning, and cam chain tensioner material to help reduce mechanical loss.• A 30% larger air filter aperture and straighter outlet tube from the airbox increase power at all engine speeds, while power at high rpm is further boosted thanks to a new twin injector, which replaces the single injector of the previous model.• With the main injector still positioned in the throttle body, a new secondary injector is positioned nearer the airbox, giving the fuel and intake air more time to mix prior to combustion, improving charging efficiency.• Repositioning of the main injector now means fuel is injected upwards so that it hits the butterfly valve directly, improving atomisation of the fuel and, in turn, combustion efficiency and throttle response. Improved throttle response is further aided by a 17% increase in fuel pressure and an updated throttle body.• When it comes to putting the new RM-Z250 engine’s increased power to the back wheel, a change to the gear ratio improves rider feeling and throttle connection. Second gear is changed to a higher ratio, going from 30/17 on the previous model to 29/17 on the 2019 machine. Final ratio is also changed, from 49/13 to 50/13.• A longer exhaust – lengthened 99mm over the outgoing model – and change to the structure and internal material boosts power across the rev range, but mostly improves power at lower engine speeds.Chassis:Weight reduction was a key objective for Suzuki engineers during development, whilst improving the 2019 RM-Z250’s handling performance.• A new frame retains fore-aft rigidity, running the length of the bike, but increases torsional rigidity by 10%. It also reduces weight by 370g.• Weight reductions continue with the swingarm, which adopts a new manufacturing process from the previous model. While the old swingarm was producing using a swaging process, hydroforming is now used, removing the need for welding and saving 80g. It also uses a tapered cross section, making it more rigid, plus a new chain guide saves another 30g and is more durable.• New seat rails are more rigid thanks to hexagonal shape, and serve to make service and maintenance easier, with removal of the air filter simpler than before.• The frame is wrapped around the new engine, but the powerplant mounts 8.5mm higher for better handling, while the mounting changes too, for more rigidity. More weight is lost with the engine mounting brackets going from steel to Aluminium, with 90g dropped.Ergonomic changes help improve handling performance and the bike’s agility.• New Renthal handlebars are straighter and enable riders to easily shift their weight to the front. They’re also 7.4mm further forward and 3.8mm lower, while the footrests are 3.3mm forward and 5.2mm higher.• Further weight is shed with a new fuel tank, which saves 312g, while a slimmer seat loses another 274g and makes it easier for the rider to move around.“THE 2019 RM-Z250’S ENGINE hAs UNdERGONE sIGNIFICANt ENHANCEMENTS.”
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