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The 2011 Honda CBR250R is an attractive, fun to ride motorcycle. But underneath its slick exterior are a host of technological features intended to enhance its performance, efficiency, and maneuverability.
Let's take a closer look at the CBR250R's technological advances, and what it took to engineer this 359 pound, single-cylinder motorcycle.
CHASSIS
The CBR250R's ergonomics are characterized by a sporty but easy reach which is designed to accommodate riders between 5 feet, 4 inches and 6 feet, 2 inches. The bike's compact proportions are aided by its chassis, comprised of a diamond-shaped twin-spar tubular steel frame with truss structures. Handling, tracking, and steering responsiveness are aided by a short 53.9 inch wheelbase and a strategically positioned engine which maximizes balance and mass centralization.There are no fewer than 18 patents relating to the frame, including a fuel filter layout that reduces weight, an under cowl structure which aids engine cooling while offering wind protection, a taillight structure that makes bulb swapping easier, and a cross frame which aids rigidity. The air cleaner not only offers more efficient engine intake, it's also more easily accessed through seat removal. These combinations of lightweight construction with strategic reinforcements help keep the CBR250R's curb weight down to 359 pounds, and 368 pounds with ABS. 37mm forks are found up front, while a Honda Pro-Link setup at the rear enables progressive shock characteristics and 17 inch cast wheels aid handling.
ENGINE
The CBR250R is powered by a single-cylinder, liquid-cooled 249cc engine that boasts 9 unique patents. The fuel-injected mill features a so-called "offset cylinder" whose centerline is moved 4mm towards the exhaust side of the engine. The purpose of un-aligning the cylinder from the crankshaft is to reduce the resistance between the piston and the cylinder during the power stroke. On the outside of the cylinder sleeves, a spiny texture helps dissipate heat and aid cooling, while keeping inner cylinder wall distortion to a minimum. The cylinders are centrifugally cast for thin, uniform wall thickness, and a striated piston skirt retains engine oil for better lubrication. An Idle Air Control Valve aids smooth throttle response and minimizes torque reaction.A dual overhead cam valvetrain design was chosen for greater combustion efficiency and in order to reduce the weight of reciprocating portion of the valves. While a DOHC setup is not unusual in a motorcycle, the CBR250R features the world's first patented application of roller rocker arms used in combination with DOHC valves. The arrangement's lightweight components enable lower overall friction levels. Within the valvetrain assembly-- which is operated by a "Silent Type" cam chain-- an O2 sensor and air injector work together along with an exhaust catalyzer for reduced emissions. Charging efficiency is enhanced by the straight path from air cleaner to exhaust pipe, and valve shape is also optimized for intake and exhaust flow. Finally, a primary balancer reduces engine vibration.
