Yamaha announces updated 2019 MX bikes

‘Tis the season to announce updated off-roaders, and this week, it’s Yamaha bringing new MXers to the forefront, with a new YZ250F and YZ85, and updates to the rest of the lineup.

The YZ250F is the big news, with a new engine with electric starter and new top end (cylinder head, piston, updated cam profile) as well as a new clutch, revised frame and bodywork, new internals for the KYB suspension, lighter wheels and most importantly, compatibility with the Power Tuner smartphone app.

The Power Tuner allows riders to upload new engine mapping to the bike from a smartphone, or to tinker with the map on your smartphone; the machine allows the rider to switch between two different riding modes, which makes testing new engine maps even more easy.

Previously, the Power Tuner smartphone tech was only available for the YZ450F.

As for the new YZ85, this entry-level two-smoker has a redesigned liquid-cooled 85 cc engine (new cylinder, head, crankcase, crankshaft, con-rod, transmission, exhaust, CDI). The chassis and brakes have been tweaked for 2019, along with suspension.

Changes to the 2019 YZ450F are far less sweeping, with some changes to the front forks.

For more details on the new 250 and 85, see the excerpt from Yamaha’s press release below.

2019 Yamaha YZ250F 

The 2019 YZ250F boasts an all-new engine design that features an electric starter, a new cylinder head, piston, cam shaft profile, cylinder geometry, larger diameter clutch and more – all working together to deliver top notch power, with even more mid-top power. 

Its bilateral beam frame is completely revamped with an optimized engine mounting position to improve the machine’s rigidity balance, which benefits cornering ability, and traction. Redesigned bodywork and ergonomics provide a lighter and more compact feel that bind rider and machine as one. The class leading KYB® suspension with updated internals provides the optimal balance between comfort and race-winning performance.  

Along with all the above, the all-new 2019 YZ250F also comes standard with a Communication Control Unit (CCU) allowing riders to connect wirelessly to their bike, and tune it according to their preferences – all they need is a phone and the Yamaha Power Tuner app. 

New engine 

For 2019, Yamaha has refined its distinct rearward-slanted cylinder design for the YZ250F engine. The liquid-cooled, DOHC 4-valve, fuel-injected engine features a forward-positioned straight downdraft intake with symmetrical intake and exhaust ports. Fuel is delivered by a lighter 44mm throttle body, through a new 12-hole Denso® injector. 

A new, higher-compression flat-top forged piston features a bridge-box design for additional strength with minimal weight. The piston, rings and DLC-coated piston pin, along with the offset cylinder configuration, all reduce friction loss and contribute to quick response. The YZ250F’s lighter and more upright cylinder, newly designed intake ports, cam profiles, high-strength connecting rod and optimized crank and counterbalancer all work together to produce more potent mid-high-rpm power with user-friendly delivery and exceptional reliability. 

The transmission and clutch have been overhauled for a more direct connection as well as enhanced durability. The transmission retains the same proven gear ratios as in the previous model, but the gears are now made of a new alloy which provides stronger shock resistance. Due to the increased strength, the gear teeth could be made thinner, reducing weight and allowing a more compact design. The clutch assembly in the YZ250F features friction plates which are now 1.6mm thicker. The increase in thickness has allowed our engineers to reduce the number of plates to by one to 8. 

The radiators and exhaust have also been modified for improved performance and weight distribution. The updated radiators are larger and angled more directly towards the incoming air stream for improved cooling under the most demanding race conditions. The innovative wraparound exhaust pipe design improves mass concentration and improves power development, with revised geometry for 2019. This layout moves the rear end of the exhaust pipe farther forward and enables a muffler position close to the center of mass. 

World’s first production 250cc class Power Tuner app 

The 2019 YZ250F is the world’s first production 250cc motocross bike with a wireless smartphone-based engine tuner. Using Yamaha’s exclusive Power Tuner app, it’s easy to choose the exact power profile for optimum race results at every track. 

By connecting wirelessly with the YZ250F’s inbuilt Communication Control Unit (CCU), riders and technicians can instantly and easily adjust air/fuel mixture and ignition timing maps to tune engine performance for various track conditions, record race log information, and monitor a range of data such as coolant temperature, intake air temperature, air pressure, battery stats and also maintenance related data such total run time and more. 

The Yamaha Power Tuner App – first released with the 2018 YZ450F – makes it possible to modify engine mapping in even greater detail than before. It also allows users to share settings among their team or with friends (along with other information) thus evolving the system into a tool that helps facilitate communication. 

Dual-mode switchable engine mapping 

Two-mode adjustable engine mapping allows the rider to adjust engine character with the push of a button, making it easy to tune the YZ250F for changing track or weather conditions. 

All-new lightweight electric start 

Utilizing a compact starter motor and ultra-lightweight lithium-ion battery, the 2019 YZ250F brings the convenience of push-button starting for quick and effortless restarts under pressure and relaxed riding when the clock isn’t ticking. Powered by a high-capacity and ultra-lightweight lithium-ion battery, the system adds minimal weight. 

New frame and optimized ergonomics 

The 2019 YZ250F’s compact frame is completely new to further refine the instinctive handling that makes this Yamaha one of the best handling machines in the class. The all-new compact bilateral beam frame features redesigned upper frame bracing, rear frame spars, swingarm pivot area and all new engine mounts that centralize mass and increase rigidity on lateral, horizontal and vertical axis to provide an ideal balance between cornering feel and straight-line rigidity. 

Simply, the new frame was designed to improve contact to the ground and provide the best possible balance of stiffness for bump absorption, and effortless cornering. 

New compact body and seat design 

Surrounding this fully redesigned chassis, the 2019 YZ250F features a new lighter, compact body from tip to tail.  The radiator shrouds incorporate a new air duct with a concave shape that not only improves styling, but is also narrower for better knee grip and overall rider movement.  The seat height has been reduced by 8mm towards the front and almost 20mm lower at the tail end, giving the rider better maneuverability on the bike.    

Easily tuned KYB® coil spring suspension 

The industry-leading, fully adjustable KYB® coil spring-type forks with speed sensitive damping receive updated settings, larger pistons and newly designed fork lugs / axle brackets to provide exceptional balance between handling and bump absorption for race-winning performance. The KYB® shock boasts new damping characteristics to match the new chassis as well as a new, lighter weight spring.  The reservoir has been increased 30cc to increase damping control during long motos. 

Lighter wheels 

Careful computer-aided refinement of the EXCEL rim’s cross-sectional profile shaves valuable unsprung weight without sacrificing durability, while more rigid wheel collars provide an improved feeling of contact to the ground when braking and a clear feeling of traction.

YZ250F Technical Highlights
•    All-new DOHC 250cc liquid cooled 4-stroke engine 
•    Power Tuner smartphone app for trackside tuning 
•    ‘On the fly’ 2-position engine mapping switch 
•    Lightweight electric starter with lithium-ion battery 
•    Slim and compact new bodywork and seat 
•    New stronger bilateral aluminium beam frame 
•    New larger diameter Air-Oil-Separate front forks 
•    Lighter rear shock with improved damping performance 
•    New heavy-duty clutch with lighter feel at lever 
•    New high-efficiency angled radiator design 
•    Redesigned air filter box 
•    Stiffer front axle mounting bracket for better feel 
•    New high specification cam chain assembly 

2019 Yamaha YZ85 

The new Yamaha YZ85 youth motocross bike features a large number of major redesigns that are focused performance and ergonomics. Featuring an all-new engine, suspension, and more, the YZ85 is designed to assist bLU cRU riders to earn their entry into the victorYZone with race winning performance and unrivaled reliability. 

All-new engine 

The 2019 YZ85 utilizes a newly designed 85cc liquid-cooled, 2-stroke engine featuring a case reed-valve intake and a mechanical Yamaha Power Valve System (YPVS). Combined with redesigned cylinder and head, crankcase, crankshaft, connecting rod, transmission, exhaust and CDI unit, this new YZ engine provides broad tractable power across the rev range without losing peak power at high RPM. 

Updated chassis and optimized ergonomics 

The 2019 YZ85’s semi-double-cradle steel frame, removable subframe and redesigned aluminum swing-arm provide a nimble feel, confident handling and ease of maintenance. The ergonomics feature a flat, comfortable seat, four-position adjustable aluminum tapered handlebars and adjustable reach levers to provide comfort and ease of movement for a wide range of young rider sizes. 

Uprated brake system 

For 2019, a new, stiffer front brake line with new routing improves braking feel, while wave-style brake discs offer improved self-cleaning and cooler-running performance. The 220mm front disc and 190mm rear disc deliver strong, precise stopping power. 

Easily tuned KYB® coil spring suspension 

The new YZ85 features KYB®’s race-proven, fully adjustable 36mm coil spring fork with one-piece outer tubes and tapered shape to provide optimal rigidity balance. This provides exceptional handling, bump absorption and ease of set-up for race-winning performance. The KYB® fully adjustable link-type shock utilizes specially designed damping characteristics to match the new chassis. 

YZ85 Technical Highlights
•    New 85cc liquid cooled 2-stroke engine with YPVS 
•    Plastic resin reed valve and new expansion chamber 
•    Increased compression ratio of 8.2-9.6:1 
•    New close ratio 6-speed transmission 
•    Light and efficient large core radiator 
•    Fully adjustable 36mm KYB® upside down front forks 
•    New impact resistant fork guards 
•    New wave discs and brake hoses 
•    4-position adjustable tapered aluminium handlebars 
•    New aluminium swingarm for easy chain adjustment 
•    Link-type Monocross rear suspension 
•    Sharp styling and factory inspired graphics