The Crea is the first light scooter from Honda powered by a new, water-cooled, OHC, single-cylinder, four-stroke engine.
Crea's aluminum frame is made of two die-cast parts.
Crea's power module integrates single-cylinder, OHC, 50-cm3 engine; belt-and-pulley CVT; rear-suspension arm; and cooling system.
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In the beginning, there was the two-stroke engine — an air-cooled, single-cylinder unit that had powered the Imperial Army's Series-6 wireless transmitter/receiver, which Soichiro Honda installed on a proprietary bicycle back in 1946. All of 500 surplus engines acquired by Honda were whisked up by the mobility-hungry Japanese within a year, providing him with sufficient funds to embark on the design and development of his own engines and motorcycles. Early Honda motorized bicycles and motorcycles, from the types A through D and F, were powered by the valveless engine type.
Honda must have had a dislike of the noisy, smelly two-stroke because he soon updated his mainstream type-D motorcycle to the type-E specifications with a new, single-cylinder, pushrod 146-cm3 engine. And in 1958 the immortal Super Cub step-through bike arrived, propelled by an all-new, OHV, single-cylinder, 50-cm3 engine, which continues to this day, with more than 27 million units sold to date. Honda had a quick glance at the two-stroke — a dominant power source in the Japanese micro vehicle segment in the Ô60s — when he launched his first four-wheel vehicle, the T360 micro truck, in 1963. It was powered by a jewel-like, water-cooled, twin-cam, inline, four-cylinder engine with a roller-bearing-supported crankshaft and displacement of 360 cm3.
Mr. Honda's disciples followed their mentor's fervent wish, improving and refining poppet-valve engines in all transport and power equipment applications — except in two areas.
One is the Grand Prix Championship motorcycle racing arena. Honda could not be accused of not trying. Indeed, it had done so very hard with an extraordinary four-stroke engine when it returned to the grand prix racing scene in 1979. The machine was the NR500, with a liquid-cooled, quad-camshaft, 32-valve (eight valves per cylinder), oval-piston V4 engine. After three years' strenuous and fruitless effort, it became apparent that it could not beat the furious two-stroke opposition, so Honda joined them with the NS500 in 1982. It won the world championship in 1983.
The other area where the two-stroke engine is the predominant power source is the light scooter segment — its cost competitiveness and superior power output within the displacement limit of 50 cm3 qualifies two-wheelers thus powered as "motorized bicycles," benefiting from a very low annual tax rate. Honda's numerous scooter models are two-stroke-powered. Honda equips certain models with an oxidizing catalytic converter integrated within the muffler to reduce exhaust emissions. A better solution to all the problems associated with the two-stroke engine — smell, emissions, noise, and temperament — is the four-stroke, agree many engineers within the Honda camp.
The Crea is the first light scooter from Honda powered by a new, water-cooled, OHC, single-cylinder, four-stroke engine, specifically designed for scooter applications. More models adopting this unit will follow, eventually replacing the entire two-stroke range. The engine displaces 49 cm3 with a long 49.0-mm stroke and narrow 36.0-mm bore. The chain-driven single overhead camshaft operates two valves via rocker arms. The engine is fed by a constant-vacuum carburetor and rated at 3.6 kW (4.8 hp) at 8000 rpm and 4.4 N•m (3.2 lb•ft) at 7000 rpm on a 12.0:1 compression ratio. The engine's induction system is fitted with a throttle sensor, whose signal is used to minutely adjust ignition timing and enhance combustion efficiency.
The Crea scooter is equipped with an electronically controlled, automatic stop-and-go (ASG) system. When warmed up, the scooter automatically cuts its engine 3 s after it comes to a complete stop and restarts the engine when the rider twists the throttle grip. If the rider for any reason gets off the seat after the engine stops, a mass-sensor inhibits the engine's restarting. The ASG system can be turned off by a switch. Honda developed a new starting motor that integrates an alternating current generator to ensure smooth starting and restarting of the engine. Honda claims the ASG improves fuel economy by 5% and reduces emissions. Fuel consumption is 61.4 km/L (145 mpg) at a constant 30 km/h (19 mph) — a typical speed around town.
The all-alloy engine is water-cooled with a system comprising a camshaft-driven water pump, a radiator integrated on the side of the engine unit, a thermostat, and a reservoir tank. The engine, cooling system, belt-and-pulley continuously variable transmission, and rear suspension's swinging arm form a modular unit that attaches to the scooter's unique, two-piece, die-cast aluminum frame.
The Crea is the second light scooter for which a die-cast aluminum frame has been adopted. The first was the sporty SZX50 for Europe, which featured a large, open-section, backbone-type, single-piece frame. A conventional, steel, tubular, welded frame consists of as many as 30 parts and requires about 4.5-m (14.8-ft) welding length, whereas the SZX50's is a single-piece construction requiring no welding.
The Crea features a flat floor or foot space, for easier every-day riding compared to the SZX's sporty, step-over, backbone type. This required a unique frame structure made of two die-cast parts. The front frame that integrates the steering head has U-sectioned side rails, while the rear frame has inverted U-sectioned rails. Bolted together, the two halves provide sufficient stiffness for the torsion and bending a two-wheeler is subjected to. A standard "Combi-brake" system enables the application of both front and rear brakes by the left-hand lever, which is more frequently used by a novice rider, to assist vehicle stability under braking. The right lever operates on the front brake only.
Jack Yamaguchi
