First Look | 2015 Yamaha YZ Model Line

2015 Yamaha YZ450F

The 2015 motocross machines continue to roll out, with images of Yamaha’s line of YZ and YZF racers being the latest to reach the public. After last year’s complete overhaul of the YZ250F and YZ450F, two bikes that have proven themselves over the last month’s professional races, it is the YZ two-stroke line that sees the bulk of the Japanese brand’s attention. Years of complaints on the dated styles of the YZ125 and YZ250 have finally been addressed, as both bikes receive full makeovers with new body kits.

Have a look at the full galleries of each bike, from the mini YZ85 to the YZ450F.
For more information, visit yamaha-motor.com.

2015 Yamaha YZ250F

Liquid-cooled, DOHC 4-valve, fuel-injected engine with the same forward-positioned, straight intake, rear-inclined cylinder, and rear-positioned exhaust layout as the YZ450F.The 4-titanium-valve cylinder head is matched to a fuel injection system that provides power at mid-to-high rpm. The fuel injection system instantly adjusts the air/fuel mixtures depending on altitude and temperature, for a hesitation-free engine that delivers no matter the conditions.

The aluminum Bilateral Beam frame offers a superb rigidity balance and provides unmatched lightweight handling.

The exhaust pipe has an innovative layout, circling the cylinder, giving the exhaust pipe proper length for an excellent exhaust pulse effect. At the same time, the exhaust pipe has three different diameters throughout the exhaust tract, bringing out excellent power characteristics. This layout allows the silencer behind the side panel, making it closer to the middle of the bike for centralized mass for superior handling.

The layout of the seat, fuel tank, air box, and wrap-around exhaust system moves the bike’s mass towards the center for exceptional handling. The front intake layout with large air filter element adds the benefit of reduced air filter maintenance due to its positioning away from dirt roost from the rear wheel.

Accessory GYTR® Power Tuner lets owners adjust air/fuel mixture and ignition timing maps to match engine performance characteristics to the rider and track conditions in a matter of seconds with the push of a few buttons.

New for 2015:

New front fork settings offer greater performance in the mid-to-end stroke

Quick-release quarter-turn Dzus® air box fasteners for tool-less access to the air filter.

Engine

A liquid-cooled, DOHC 4-valve, fuel-injected engine with the same forward-positioned straight intake, rear-inclined cylinder and rear-positioned exhaust layout as the YZ450F. The engine, with its straight and symmetrical intake and exhaust ports and compact, high-compression combustion chamber, delivers outstanding engine character in the highspeed range.

The adjustable fuel injection system uses a 44mm throttle body fed by a high-pressure battery-less electric fuel pump. This ensures optimum fuel atomization and air/fuel calibration for excellent rideability in a wide range of riding conditions. The system controls the volume of fuel injected and the ignition timing based on engine rpm and throttle opening, providing hesitation-free response and controllability.

Various detailed design measures are adopted to reduce horsepower loss. The forged 2-ring piston is light weight and is cooled by an oil spray jet. In addition, the compression ring is a single-ring design instead of the conventional two ring. This piston and rings, along with the offset cylinder configuration, reduce friction loss and contribute to quick response. What’s more, the specs for the intake/exhaust ports, cam profiles, ECU, carburized crank, optimized balance ratios for the crank web, transmission, clutch design, and other features, all work together to create the YZ250F’s outstanding engine character with power output in the high-rpm range.

As with the YZ450F, an innovative exhaust pipe design is adopted to increase mass centralization and improve power development characteristics. This layout moves the rear end of the exhaust pipe farther forward and enables a muffler position close to the center of the mass. Adjustments are made in the pipe diameter in its various sections resulting in excellent exhaust pulse effect that contributes to high rpm power output.

The compact wet sump lubrication system with piston cooler spray jet maintains excellent engine durability and eliminates the need for an oil tank, which lowers engine weight. This creates a more compact engine that contributes to mass centralization and unmatched handling.

The transmission and shift mechanisms reduce drive-force loss during gear changes and produce smoother shift operations and surer shift action.

Chassis/Suspension:

The aluminum muffler is positioned closer to the machine’s center of gravity as it is almost completely hidden by the side number plate. The layout contributes to centralized mass for a lightweight handling feeling.The front suspension has proven KYB® air-oil separated forks with stiffer fork springs, new valving and a new fork outer tube to improve performance in the mid-to-end stroke and aid fork bottoming resistance. The rear suspension also features settings optimized for ideal damping characteristics to match the chassis dimensions.

The large diameter 22mm front axle and top triple clamp increases rigidity for excellent handling and front end feel. The handlebar mounts are rubber mounted to improve comfort and reduce handlebar vibration.

The air filter is positioned away from the rear wheel which means less maintenance for the rider.

Additional Features:

“In-mold graphics” technology is a method in which the graphics are molded into the radiator shrouds for improved decal durability and reduced scratches.Riders have a choice of two color options: Team Yamaha Blue/ White or White/Red.

2015 Yamaha YZ450F

YZ450F’s revolutionary rearward-slanted-cylinder design is an innovative approach to achieve unmatched mass centralization. Concentrating the motorcycle’s heaviest components (engine mass, fuel tank, exhaust system, and airbox) toward the center of the machine, as well as the rotational mass of the valve train, helps achieve superior, nimble handling.

The 4-titanium-valve cylinder head is matched to a fuel injection system that provides superb power feeling across the rpm range. The adjustable fuel injection system uses a 44mm throttle body fed by a high pressure battery-less electric pump to ensure optimum fuel atomization and air/fuel calibration for a wide range of riding conditions. The YZ450F instantly adapts to changing air/fuel mixtures depending on altitude and temperature, for an engine that delivers no matter what conditions.

The aluminum Bilateral Beam frame features new motor mounts to improve the machines handling character and offers a superb rigidity balance and, with class-leading front and rear suspension, provides unmatched lightweight handling and cornering.

Industry-leading suspension with refinements to internal and external components and settings result in superior handling.

Accessory GYTR® Power Tuner lets owners adjust air/fuel mixture and ignition timing maps to match engine performance characteristics to the rider and track conditions in a matter of seconds with the push of a few buttons.

New for 2015:

Stiffer fork springs, new valving and a new fork outer tube improve performance in the mid-to-end stroke and aid fork bottoming resistance.

Quick-release quarter-turn Dzus® air box fasteners for tool-less access to the air filter.

A new steel bottom engine bracket has been designed for increased rigidity balance and damping feel.

New Dunlop® MX52 tires offer excellent traction front and rear, especially on hard surfaces.

Engine:

The high-performance ECU provides great bottom end torque plus delivers a strong feeling of power from 3rd gear up while the gear ratios lengthen the powerband and heighten the feeling of power in 2nd and 3rd gear.

The valve mechanisms and cylinder head feature specs that take performance to the next level, resulting in added power and outstanding performance.

The exhaust pipe has an innovative layout, circling the cylinder, giving the exhaust pipe proper length for an excellent exhaust-pulse effect. At the same time, the exhaust pipe has three different diameters throughout the exhaust tract, bringing out excellent power characteristics. This layout allows the silencer to be behind the side panel closer to the middle of the bike which centralizes the mass for superior handling.

The compact wet sump lubrication system with piston cooler spray jet eliminates the need for an oil tank, reducing engine weight. The water pump employs a plastic resin impeller for further weight reduction. The reduced size of the crankcase enabled by this lubrication system design is a major factor in making it possible to mount the 450cc engine on the compact frame to deliver precise and instinctive handling.

The accessory GYTR Power Tuner can simplify the work of adjusting fuel injection volume and ignition timing settings to fit personal preferences or track conditions.

Chassis/Suspension:

A Bilateral Beam frame is adopted and the overall dimensions are roughly the same as the frame of the 2013 YZ250F. This gives the YZ450F a compact chassis that provides the most instinctive handling in the 450 motocross class.

The aluminum muffler is positioned closer to the machine’s center of gravity as it is almost completely hidden by the side number plate. The layout allows a shorter, lighter sub frame and also contributes to mass centralization for lightweight handling feel.
The front suspension has proven KYB® air-oil separated forks with stiffer fork springs, new valving and a new fork outer tube to improve performance in the mid-to-end stroke and aid fork bottoming resistance. The rear suspension also features settings optimized for ideal damping characteristics to match the chassis dimensions.

The large diameter 22mm front axle and top triple clamp provide rigidity for unmatched handling and front end feel. The handlebar mounts are rubber mounted to improve comfort and reduce handlebar vibration.

The fuel tank and air cleaner box give the machine a slimmer feeling between the legs as well as positions the fuel tank mass closer to the center of the bike which improves handling feel. Furthermore, the air box can be accessed without removing the fuel tank for easy serviceability of the large air cleaner element.

A narrow radiator design contributes to slimming down the radiator panel area.

Additional Features:

Riders have a choice of two color options: Team Yamaha Blue/ White or White/Red.

PAGE TWO: 2015 YZ125 & YZ250
PAGE THREE: 2015 YZ85

Pages: 1 2 3