Design & Styling Of Yamaha R15 Special Edition

R15 Special Edition has all the characteristics of motorcycles which designed by Yamaha to represent the R series which 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 of R15 Special Edition 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 R15 Special Edition. An important point to note is that this motorcycle is not a scaled-down version of YZF-R1 or YZF-R6. R15 Special Edition'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. rst for the Indian market. When viewed from the front, Yamaha R15 Special Edition  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.

Engine Of Yamaha R15 Special Edition

R15 Special Edition 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 R15 Special Edition 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 of R15 Special Edition 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 R15 Special Edition. 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.

Chassis Of Yamaha R15 Special Edition

R15 Special Edition 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 of R15 Special Edition 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 of R15 Special Edition combined with the effects of the linked type monocross suspension achieve good riding comfort, agile handling, and turnability, hardly ever causing bottoming out. In order to maximize the efficiency of the fuel injector, which injects the optimum amount of fuel for different amounts of intake air, R15 Special Edition 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). R15 Special Edition 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.