Yamaha YZF R15

 

Humachine Technology

A sharp form that cuts through air. Inheriting the “R series” gene.

YZF-R1 and YZF-R6 are equipped with under cowls that are based on the image of a diffuser, to give them the best form for aero-management. These are not cowls for simply enclosing the engine, but forms composed of blade surfaces that actively control airflow. This spirit has been directly inherited by YZF-R15.

“Harmony between rider and machine.”YAMAHA’s Humachine Technology involves studying the form of the motorcycle actually in motion with the rider on it. The R series is the embodiment of 1) wide frontal space that protects the rider, 2) easy to ride seating area that gives riders the freedom of movement and allows them to steer effectively, 3) the glamorous tail treatment that takes into account the management of airflow behind the rider, and 4) a sexy racing form that brings all 3 of these elements together in a harmonious package. These characteristics have been splendidly reproduced in YZF-R15.

Additionally, the designs were developed in the same modeling room where YZF-R1 designers worked. Information was shared, ensuring that the R lineage would be transmitted. In addition, the model also incorporates a multitude of adjustments for the Indian market including seat shape that allows for tandem riding (integrated with the main seat), tandem grips that are easy to grip and also contribute to the supersport design, and a riding position that takes into account comfort, etc. In other words, YZF-R15 is characterized by a hybrid design that combines the world-class design of the “R” series with localized functions. YZF-R15 was created to lead the supersport category in India.

The “R” Design

This characteristic of motorcycles designed by YAMAHA as represented by the R series reflects the philosophy running through these models -- expressing performance visually.

For example, YZF-R6 shows a strong body line that springs up in a single line from the rear axle to the pivot and then to the head pipe. This is a visual expression of the straight shape of the Deltabox frame. These elements are a visual expression of “frame rigidity.” Viewed from the side, the shape created by the side panel and the upper surface of the tank creates an impression of the center of gravity shifting to the front tire. This is a visual representation of how the front tire grips the road in its sporty running performance. Needless to say, YZF-R1, with its athletic build, is also a visual expression of performance. A characteristic of the R series is that, when you view the machine, you get a sense of its concept and performance.

This philosophy has been fully transmitted to YZF-R15. An important point to note is that this motorcycle is not a scaled-down version of YZF-R1 or YZF-R6. YZF-R15’s design is based on having an excellent engine cooling method.

The shape of the cowling around the radiator area was determined so that the shapes of the air intake area and the rear outlet area where the air is scooped out are optimized to improve radiator efficiency. As for the outlet area, the mid-cowl area was designed using sculpturing 3D methods to create a three dimensional shape with a sense of volume. This resulted in an outlet area through which air is directed outwards with minimal resistance. We were able to present the new R series also in terms of design, and we have been able to maximize the performance of the liquid cooled engine, which will be a first for the Indian market.

When viewed from the front, it gives a sense of volume that seems well beyond its 150cc displacement. This does not simply mean that it is voluminous, but that it is grounded in the Art of Engineering which transforms function into art.

Linked type Monocross suspension

YZF-R15 is equipped with a linked type monocross suspension that delivers a comfortable ride and a cushioning performance that is less prone to bottoming out. In particular, it reduces annoying “sinking” when riding tandem.

The linked monocross suspension consists of a link mechanism sandwiched between the rear arm and cushion unit to create changes in the lever ratio based on the lever effect. When the shock absorber is almost fully extended, the lever ratio is high and therefore the spring is soft, and the damper works softly as well. As the shock absorber strokes in, the lever ratio gradually decreases and the spring rate increases. Eventually, when it is nearly fully stroked in, the lever ratio becomes small and the spring becomes hard and strong. The damper also becomes hard. By making changes to the lever ratio in this way, we were able to achieve soft riding comfort as well as excellent damping under intense load conditions.

The optimization of the frame and rear arm rigidity of the Deltabox Frame combined with the effects of the linked type monocross suspension achieve good riding comfort, agile handling, and turnability, hardly ever causing bottoming out.

As the heir to the YAMAHA R series, YZF-R15 has inherited the series’ agile handling performance.

Deltabox Frame

The frame, which forms the basis for riding comfort and handling performance, is a Deltabox frame which delivers superior rigidity balance.

This frame was designed to provide the best balance in longitudinal, lateral, and torsional rigidity. The synergy created by optimizing each dimension delivers a solid riding feel as well as comfort and agile riding performance.

The Deltabox frame was commercialized based on the experience and know-how accumulated through YAMAHA’s involvement in Moto GP since the early 1980s. This type of frame is currently used in YAMAHA’s R series of sport models. The engine is mounted on rigid supports; one on the head side and two on the case side; so that the engine itself becomes a structural member contributing to body strength and rigidity. The engine’s low vibration makes rigid supports possible, ensuring low vibrations and excellent balance of rigidity. Torsional rigidity refers to the frame’s resistance to deformation when a twisting force is applied to the pivot with the frame’s head pipe held in place.

Fuel Injection

Fuel injection is used to ensure excellent fuel efficiency as well as environmental friendliness.

The two components of the fuel injection mechanism used in YZF-R15, a) the sensors that gather information on the engine’s operation, and b) the fuel supply system that supplies gasoline, have both been designed to be lightweight and simple. The sensor component uses only 4 sensors (Red blinking points) to gather large amounts of information relating to engine operations, which is sent to a small 26-pin ECU, which in turn calculates the optimum fuel supply. The fuel supply component consists of a small, fuel pump, modularized regulator and filter, and a small injector, all of which come together to enable a lightweight, compact form. The injector injects finely atomized spray of fuel through 6 hole type injectors.

In order to maximize the efficiency of the fuel injector, which injects the optimum amount of fuel for different amounts of intake air, YZF-R15 is equipped with a large 3-liter air cleaner. The duct area of the intake duct was designed optimally to optimize the flow of intake air.

Additionally, the use of a 4-valve combustion chamber (a combustion chamber with 2 intake and exhaust valves each) has allowed designers to layout the spark plug at the center of the combustion chamber for better flame propagation. This also increases the total valve area relative to the 2-valve chambers for improved intake/exhaust efficiency (volumetric efficiency). YZF-R15 is fitted with a hemispherical 4-valve combustion chamber, a configuration that allows intake and exhaust valves to be laid out in the smallest size possible.

In addition, the intake and exhaust valve angles have been kept small to achieve optimum combustion chamber configuration. We also aimed at minimizing the surface area/volume ration (S/V ratio) in the combustion chamber, which is key to improving fuel efficiency. In conjunction with the fuel injection system, this combustion chamber contributes to comfortable riding during long-distance rides as well as during medium to high-speed riding.

YZF-R15’s engine delivers excellent response, fuel economy, is environmentally friendly and a comfortable ride.

DiASil Cylinder

The DiASil Cylinder was born from YAMAHA’s world-class aluminum die casting technology.

DiASil Cylinders are all-aluminum cylinders made by YAMAHA’s proprietary aluminum die casting technology. An aluminum alloy with 20% silicon content is used to create a very hard, reliable cylinder surface, making conventional iron sleeves obsolete. As a result, the entire cylinder can be made of aluminum, a better conductor of heat, which means the cylinder delivers better heat dissipation and less weight. (Aluminum’s heat conductivity is 3.1 times that of iron.)

YZF-R15 is equipped with this all-aluminum cylinder called the DiASil Cylinder and a forged piston, the same type of piston used in YAMAHA’s supersport bikes. The fact that both the piston and cylinder of YZF-R15 are all-aluminum ensures excellent heat dissipation, eliminates heat-induced engine power loss, and helps improve fuel efficiency. The DiASil Cylinder is given a special surface treatment to prevent oil evaporation from the cylinder’s surface and improve oil consumption. The cylinder also has excellent hardness and is considerably resistant to wear compared to conventional iron sleeves.

Additionally, the piston is made in a forging process, the optimum way of achieving lightweight designs.The reciprocating mass with the forged piston is approximately 20% less ( according to Yamaha test ) than with an engine of the same displacement fitted with a conventional cast aluminum piston. Resulting in an invigorating feeling when revving up.

Conventional pistons are typically made in a casting process where molten aluminum is cast in a mold. YAMAHA developed its proprietary “controlled forging technology” in 1997, which enables mass production of forged aluminum pistons. These pistons have been used in sport models such as the R series. The same manufacturing process was used to develop YZF-R15. Forged pistons retain the excellent strength of aluminum alloys because the metallurgic matrix of aluminum is not affected during the fabrication process. Therefore, the piston can be made lighter and thinner.

YZF-R15 is packed with state-of-the-art technology that is used in the world’s supersport bikes.

Liquid-cooled

First India-made model with cooling method in the Indian market! Liquid-cooled engines provide stable performance, reduce vibrations, and offer a high quality ride.

One characteristic of YZF-R15’s new engine is that it is liquid-cooled. The engine is surrounded by a water jacket in which coolant liquid circulates to cool the engine. While this method is widely used in automobiles and large capacity motorcycles, there are very few examples of motorcycles of this class due to increased weight from components such as radiators. YZF-R15 uses a special compact and lightweight aluminum radiator and a body design that utilizes airflow for heat dissipation. This has enabled us to create a lightweight, compact body while retaining its stable performance.

The benefits of using this method include stable performance during long-distance, high-speed riding and hill climbing. A liquid-cooled engine does not need heat-dissipating fins and therefore the engine is able to deliver its best performance without being affected by temperature. Additionally, because the head and cylinder are enclosed in a water jacket, mechanical noise from the engine is reduced dramatically.

The newly developed engine delivers agile riding performance, and excellent performance on straight stretches of road as well as on winding roads. YZF-R15 also delivers excellent environmental performance. These traits are a must for an “urban supersport.” The ride is unprecedented in terms of both excitement and quality.

Drawing on 10 years of YZF series development with a new fuel-injected engine and Deltabox frame The new YZF R15 invites you to “enjoy riding”

Engine type
Liquid-cooled, 4-stroke, SOHC, 4-valve

Cylinder arrangement
Single cylinder

Displacement
149 .8cc

Bore & Stroke
57×58.7mm

Compression ratio
10.4:1

Maximum power
17PS / 8,500rpm

Maximum torque
15 N.m / 7,500rpm

Starting system
Electric Start

Lubrication
wet sump

Engine oil capacity
1.0 liters

Fuel tank capacity
12 liters

Fuel supply system
Electronic fuel injection

Ignition system
T.C.I

Primary / Secondary reduction ratio
3.042 / 3.000

Clutch type
Constant-mesh wet multi-plate

Transmission type
Return type 6-speed

Gear ratios
1st=2.833, 2nd＝1.875, 3rd:=1.364,
4th=1.143, 5th=0.957, 6th=0.84

Frame type
Deltabox Frame

Caster / Trail
26° / 100mm

Tire size (Front / Rear)
80/90-17 / 100/80-17

Brake type (Front / Rear)
Hydraulic, single disc (Front / Rear)

Suspension type (Front / Rear)
Telescopic / Linked type Monocross

Headlight
12V35W / 35W＋35W

 

Overall length x width x height
1,995mm x 670mm x 1,070mm

Seat height
790mm

Wheelbase
1,290mm

Minimum ground clearance
160mm

Dry weight / Curb weight
120kg / 131kg