The all new Yamaha YZF-R3 mounts a newly developed 321cc, liquid-cooled, 4-stroke, in-line 2-cylinder, fuel-injected engine. With all-new engine and chassis designs, the YZF-R3 sports a solid combination of class-leading power and a lightweight body that achieves high levels of riding performance and styling worthy of the “superbike” moniker. At the same time, it offers the nimbleness and easy-to-use character for daily use as well as riding excitement in a variety of usage scenes. The YZF-R3 Sports Model boasts increased displacement and a lighter yet higher-performance chassis, a winning combination that immediately establishes the model as one of the most competitive entries in its class. The new product offers agile handling from the lightweight body, mass centralization measures, etc. It aims to achieve an excellent balance of both high performance and fuel efficiency and a riding position that is good for sporty riding and results in less rider fatigue.
A newly developed 321cc, liquid-cooled, 4-stroke, in-line 2-cylinder, DOHC, 4-valve fuel-injected engine that achieves the model’s concept is adopted. With a bore x stroke spec of 68.0 mm x 44.1 mm and a compression ratio of 11.2:1, this engine generates its maximum power output at 10,750r/min and maximum torque at 9,000r/min. A prominent feature of this newly designed engine is that it employs the latest combustion analysis technology to ensure a sufficient volume of air-fuel mixture intake and actively inducing a swirl and tumble flow as it enters the combustion chamber to promote rapid combustion.
To ensure this sufficient volume of air-fuel mixture intake, a 26.0 mm diameter intake valve and a 22.5 mm exhaust valve are adopted, and are set at a tight 24.75° angle to help create a compact combustion chamber. Fresh air from the down-draft intake type throttle body is mixed with the injection of finely atomized fuel particles (a few tens of microns in size) and effectively directed into the combustion chamber to increase the combustion speed and minimize the occurrence of unburned fuel at the end of the combustion process, resulting in excellent power output and torque characteristics. This makes for good ridability in the low- to mid-speed range, good revving feeling up through the mid- to high-speed ranges and ensures a good balance with fuel economy and other factors
FORGED PISTONS & DIASIL CYLINDERS
Forged aluminum pistons that help reduce engine vibration
Forged pistons known for their lighter weight and excellent strength at high temperatures are adopted. These pistons have a reciprocating mass that is approximately 10% less than cast pistons, which help reduce vibration in the machine’s body.
Yamaha perfected a controlled forging technology that enabled mass production of high-precision pistons and made it possible to adopt them on engines for production sport models. The main advantages are the reduced weight compared to a cast piston, and the excellent balance of strength and rigidity at high temperatures. The strength of aluminum is temperature-dependent. Most aluminum alloys have high strength levels at normal temperatures, but their strength can diminish at temperatures over 300° C. When the strength of cast pistons and forged pistons are compared, there is little difference in strength in cool conditions, but the forged piston retains roughly twice the strength of a cast piston when heated to over 300° C. The top of a piston in a 4-stroke engine reaches temperatures of 300 to 350° C (figures based on Yamaha testing). This is why Yamaha chooses to use forged pistons in its high-performance sport models to ensure greater reliability.
DiASil Cylinder contributing to reduced weight
Yamaha’s all-aluminum “DiASil Cylinder” is adopted to ensure excellent heat dissipation. In addition to its good heat dissipation properties, this cylinder also slows oil deterioration (consumption), maintains a more perfectly cylindrical shape that reduces horsepower loss (enabled by the use of low-tension piston rings) and other benefits. [Reference] The DiASil Cylinder is an all-aluminum cylinder made possible by exclusive Yamaha casting technology. This technology enables the casting of a cylinder from an aluminum alloy with 20% silicon content, which previously was considered too difficult with conventional casting technology. The resulting DiASil Cylinder has the advantages of a cylinder wall with a highly friction-resistant microstructure, excellent heat dissipation qualities, reduced weight and more. It is a proven technology used on many Yamaha scooter and commuter models today. This is the first time it is adopted on a 2-cylinder engine.
As one of the measures to increase the compactness of the engine, shorter connecting rods are adopted. At the same time, an offset cylinder design is used to reduce horsepower loss and achieve an excellent level of power output. An offset cylinder is one in which the center of the cylinder is offset by a few millimeters from the center of the crankshaft to eliminate the force of the piston’s motion towards the cylinder wall at the moment of maximum internal cylinder pressure during combustion (see diagram at the right). This reduces friction loss and brings out the power produced by combustion more efficiently.
A steel diamond type frame has been newly designed for this model. Using the latest structural analysis technology, it has been made lighter while maintaining excellent rigidity balance. The main pipes are made of 35 mm-diameter steel pipe, used in a simple design with little crimping, bending or welding. The engine is mounted to this frame with three rigid mounts and one rubber mount. By using rigid mounts, the crankcase becomes a stressed structural member of the chassis and contributes to weight reduction. The seat area is positioned low and is slim in design to contribute to easier leg reach to the ground.
A multi-function instrument panel is adopted. On the left is an analog (needle) tachometer and on the right is a digital speedometer. In the center is the same type of shift timing indicator lamp as on the YZF-R1 and YZR-M1. Other display functions include (1) a gear position indicator, (2) a fuel gauge, (3) a water temperature gauge, (4) real-time fuel economy and average fuel economy indicators, (5) a clock, (6) two tripmeters, (7) an oil change indicator and more.
The rear suspension is a Monocross type that enables greater wheel travel than the actual length of the shock absorber’s stroke. It is lightweight and can contribute to better mass concentration, plus it allows more design freedom for the layout of the exhaust system. It is manufactured by KYB.
The shock absorber is mounted with the optimum lever ratio. Over its 125 mm span of wheel travel, it provides a good balance of cushioning performance during initial stroke and damping performance when all the way at the limit of the compression stroke. The plentiful amount of rear wheel travel combines with the effects of the optimized layout of the drive axis, rear axle and the pivot axis to give the rider a clear and enjoyable feeling of the shifting of machine weight during acceleration and deceleration that is one of the delights of motorcycle riding.
Disc brakes are adopted to ensure excellent stopping power and good operational touch. The front brake has a floating-mount 298 mm disc and is coupled with a 2-pot caliper. The rear brake has a floating-mount 220 mm disc and a 1-pot caliper. [Reference] A floating-mount disc brake is one in which the mounting assembly that attaches the disc to the wheel and the friction surface of the brake pads are independent. This structure provides good resistance to heat distortion and absorbs the fluctuations of the disc itself to provide a good operational touch. It also helps reduce brake squeal.
SPORTY SHORT MUFFLER
A 2-into-1 exhaust pipe and a short muffler are adopted. Positioning the muffler compactly and closer to the center of the chassis in the lower area contributes to mass centralization. Furthermore, its shape suggestive of the YZF-R6 creates a sporty impression, while at the same time its triple expansion chamber design effectively reduces noise and produces a pleasing exhaust note.
Built into the muffler is a 3-way catalytic converter. There is an O2 sensor detects the remaining oxygen in the exhaust and sends the information to the 16-bit ECU, which provides optimal fuel injection volume accordingly and results in the catalyzer functioning to effectively clean the exhaust.
SPLIT HEADLAMPS AND AIR DUCTS
Ten-spoke cast aluminum wheels with an optimal balance of strength and rigidity are adopted. While contributing to the reduction of weight in the un-sprung components, the wheel design also serves to optimize the gyro moment of the front assembly and contribute to light, agile handling.
The KYB-made front suspension uses a regular (upright) type fork with 41 mm diameter inner tubes, the largest in this class. This is mounted with an aluminum handlebar crown and aluminum under-bracket in an assembly that provides 130 mm of stroke and a feeling of rigidity that makes it easier for riders to follow the lines they want through curves.