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.
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.
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.
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.
