Suzuki Motor of America has released technical details about its all-new 2019 RM-Z250 motocross bike. The yellow 250 four-stroke motorcycle features an upgraded engine, new suspension components, several chassis changes, and updated bodywork similar to that of the RM-Z450, which was completely redesigned last year.
The engine features a new cylinder head with a different intake port shape and finish that is designed to deliver better throttle response and power. It also has a new dual injector EFI system that is intended to increase performance through the entire rpm range, especially in the high rpm. The intake camshaft profile is new and has more valve lift, the machining process at the piston pin holes is changed to reduce stress at the piston crown and increase reliability, and the cam chain tension adjuster and guide have been redesigned to reduce friction and mechanical loss.
The RM-Z250 has a new throttle body without control linkage, a new high-capacity fuel pump that has 17 percent more output pressure, and the air filter opening is 30-percent larger with a more direct air cleaner outlet tube path into the throttle body for increased airflow. The exhaust system is all-new with a longer header pipe, a tapered midsection, and a four-layer design muffler that maintains compliance with AMA sound regulations. Lastly, the five-speed transmission has been updated with a new second-gear ratio and overall final ratio, the Suzuki Holeshot Assist Control (S-HAC) has been revised, and the EFI system can still be tuned with Suzuki’s fuel couplers.
The 2019 RM-Z250 is equipped with a new KYB AOS (Air-Oil Separate) coil-spring fork along with a new KYB shock. The linkage has also been changed to match with the new shock and chassis set up as well.
The Suzuki features a new aluminum frame that is 370 grams (approximately 0.8 pound) lighter than the previous-generation frame and also has a 10-percent increase in torsional rigidity. The position of the engine in the new frame is changed so the crankshaft sits higher in the chassis and the design of the rear upper engine mounts have been updated to a pair of mounts that are outboard of the cylinder head. The engine mount material has been changed from steel to aluminum to reduce weight as well. Another update to the RM-Z250 chassis is the new swingarm that is shaped using a hydroforming process that maintains strength but reduced the weight by 270 grams (approximately 0.6 pound).
The subframe has new hexagonal aluminum rails for lighter weight, a slimmer appearance, and easier air filter access. They are also moved inward to help slim the bodywork, are are also raised to provide additional space for the larger air filter. The bodywork and styling has also been changed to match that of the RM-Z450, which was completely redesigned last year. The Renthal Fatbar is new and has a straighter bend with less pull-back than the previous model. In addition to the ergonomic changes from the new bodywork and handlebar, the footpegs are moved 3.3mm (approximately 0.12 inch) forward and 5.2mm (approximately 0.2 inch) upward, while the handlebar grip position is moved 7.4mm (approximately 0.3 inch) forward and 3.8mm (approximately 0.15 inch) downward.
The brakes have been upgraded with the front using a larger 270mm wave-style rotor and the new lever is a pushrod type that is designed to more effectively transmit the squeezing force that the rider applies to the master cylinder. The rear brake master cylinder is a new design that hugs the frame beam intended to prevent mud from collecting on it and from catching on the rider’s boots. The brake pad material has been changed to improve performance as well.
The new plastic fuel tank weighs 227 grams (approximately 0.5 pound) less than the prior model’s aluminum tank. A new slimmer seat features revised foam density and weighs 227 grams (approximately 0.5 pound) less than the previous year models. The Suzuki has a lighter upper fork bracket and a lighter chain guide as well. Lastly, the RM-Z250 is the first production bike to come stock with Dunlop’s all-new MX33 soft-to-intermediate-terrain tires.