From Honda's press material:
Keeping it simple, keeping it real.
One of the things riders find most appealing about standard/naked-style motorcycles is their stark, honest simplicity. Nothing extraneous has been added, and anything that doesn't contribute fully to the bike's fine balance of exhilarating performance and broad-ranging versatility has been ruthlessly shorn away. It's a classic concept, one that's stood the test of time.
That describes Honda's 2004 599 precisely. Yet while the 599's street creed draws largely on its classic simplicity, it's also bolstered by bright-think technology, in ways you might expect-and in ways that will surprise you.
The 599's engine, for example, should look quite familiar. It's the same basic powerplant found in the CBR600F3: a modern 600cc liquid-cooled inline-four with oversquare bore and stroke dimensions (65.0mm by 45.2mm), and double overhead cams actuating 16 valves. Compared to the F3 engine, the 599's features flat-slide CV carburetors with 2mm-smaller bores, from 36mm to 34mm. Engine differences are designed to broaden the already-wide powerband, and put extra punch at low-to-midrange rpm-the hot tip for real-world street use. The current 599 takes that idea a step further, with slightly narrower intake ports; two separate maps in the computerized digital ignition for the outboard (1, 4) and inboard (2, 3) cylinders; and new cam timing. Taken as a whole, the changes add peak power as well.
Spent combustion gases exit through a new, stainless steel four-into-two-into-one exhaust system with a larger-capacity muffler. California models house a 300-cell catalyzer in the new muffler. The catalyzer, a new air injection system with internal rather than external lines, and a 20mm wider radiator for enhanced cooling capacity all help reduce emissions of hydrocarbons, carbon monoxide and oxides of nitrogen.
The addition of a catalyzer exhaust led to the most significant change to the engine of the California-model-a fuel-shutoff system. Catalyzer elements work at extraordinarily high temperatures, almost 600 degrees Fahrenheit, and if any raw fuel reaches the super-heated element, the subsequent heat of combustion would damage it severely. With conventional carburetors, though, unburned fuel can pass directly through the combustion chambers to the exhaust if the ignition is cut, such as turning the ignition off while revving the engine, or if the rev limiter kicks in.
Rather than add the complication of programmed fuel ignition, Honda engineers instead modified the carburetors, adding a solenoid that controls air entering the float chambers. The solenoid reacts instantaneously to ignition status. During normal operation, the float chambers draw air from a sub-air-cleaner assembly. But if there's a loss of electricity to the ignition, and, subsequently, to the spark plugs, the solenoid switches airflow from the sub-air-cleaner to the intake ports. That equalizes the air pressure in both the ports and float chambers, which instantly stops fuel from entering the combustion chambers. It's a clever bit of engineering that allows using a carburetor system with a catalyzer-something not possible before.
The 599's more powerful engine is used as a stressed member in the unique Mono-backbone frame borrowed from Honda's popular domestic-model Hornet 250. Rectangular steel tubing is used to create a simple structure that's both extremely light and rigid. A large main backbone reaches from the steering head all the way to the back of the engine cases, and ties in the engine and the aluminum swingarm's pivot. Die-cast aluminum plates bolt to the frame, and support the ends of the pivot.
Suspension is via conventional telescopic fork in front, and a rear shock (with seven-position spring preload adjustability) that bolts directly to the swingarm and the frame. Again, it's an elegantly simple solution, improved on the current 599 with revised spring and damping rates front and rear that hones the bike's already razor-sharp handling. The 599 can also boast of race-ready rolling stock with ultra-wide rims-3.50 x 17 front, 5.50 x 17 rear-shod with appropriately sticky tires. Braking hardware includes twin 296mm floating front rotors grasped by twin-piston calipers, and a 220mm rotor/single-piston caliper combination in back.
This latest middleweight 599 has far more aggressive styling than before, but there are functional benefits as well from the bold new look. The fuel tank now has a capacity 1 liter larger, which contributes to nearly 10 percent more touring range. There's also a new, longer saddle that not only gives riders more room, but also positions them 15mm farther forward. That shift aids mass centralization, and contributes to the 599's balanced handling.
Likewise, the new round, larger-diameter headlight not only gives the Hornet a more purposeful face, it also represents a quantum step in nighttime illumination. A lightweight polycarbonate lens in front of a die-cast aluminum reflector body replaces the previous model's glass lens/steel body combination. What makes the difference in lighting, though, is the reflector's computer-designed free-form surface, and two single-filament 55w H11 bulbs in place the usual dual-filament H4 bulb. The upper low-beam projects bright, high-visibility light that covers 70 percent more area than an equivalent round single-beam headlight with the same rated output. And the lower high-beam further extends the area illuminated by another 60 percent, throwing light more than 60 feet farther than a conventional high beam. What's more, the 599's twin bulbs offer an average life 400 percent longer than dual-filament H4 bulbs.
Sitting directly behind this remarkable headlight is new, fully electronic instrumentation, with analog speedometer and tach, and large, easy-to-read white faces. LCD displays provide information on coolant temperature, the odometer, twin trip meters and digital clock. Less visible is Honda's devotion to making small yet significant detail changes, such as bigger rubber grommets under the fuel tank which reduce noise, and rubber mounts for the saddle to minimize vibration.
Simple touches, right? But they're also the very things that will endear themselves to owners every single time they go out for a ride. And the other refinements that have gone into this latest 599 just reinforce the basic personality it's had since the beginning. It's still the most sporting and most capable of the middleweight standard/naked-style motorcycles, yet it retains the comfort, versatility and ease of use expected of such bikes.