Honda

HONDA

NEW FOR '91

A RENEWED CBR HEATS UP THE 600 CLASS

HONDA'S HURRICANE 600 blew into America in 1987 and quickly proceeded to rewrite the rules for 600cc sportbikes. But by the looks of the new CBR600, that original Hurricane was little more than a storm warning of things to come.

That's quite a statement considering in the intervening four years, the CBR has remained at or near the top of the class. It exhibited a remarkable balance between real-world ridability and high-performance expertise. The Honda was easily the best all-around middleweight until 1990, when Kawasaki introduced its ZX-6. a bike which upped considerably the performance and comfort quotients of the 600 class.

With the introduction of its completely redesigned 1991 CBR600, Honda looks determined to reclaim the territory it lost last year, when it only slightly changed the CBR. The 1991 model has been revised so heavily that Honda is calling it an allnew model, the bike sharing no parts with the earlier version, making it a true second-generation CBR.

The foundation of the bike is its engine. Honda claims the 599cc, liquid-cooled inline-Four produces 100 horsepower, 6 horsepower more than last year’s engine. To get that increase, almost every part in the engine has been changed. The camshaft drive has been moved from the middle of the engine to the right-hand side—like that on the original Kawasaki 900 Ninja engine—to allow a more compact and lighter cylinder and head design. Also, the cylinders are now cast into the upper crankcase, another weight-saving move.

Bore and stroke is now 65 x 45.2mm—the older version’s was 63 x 48—and the pistons, crankshaft and connecting rods are lighter for less reciprocating mass, which, in conjunction with the shorter stroke, allows a 1 3,000-rpm redline, 1000 rpm higher than before. Furthermore, the valves are bigger, and have a narrower included valve angle— 16 degrees as opposed to the older unit’s 19 degrees. They also used a shim-under-bucket adjustment system, which provides more reliable operation at higher rpm. The carburetors are 34mm flatslide downdraft CVs, fed through a 6.2-liter airbox. The exhaust system is a 4-into-2-into-l unit. The engine now comes with a liquid-cooled oil cooler.

In part because the engine is physically smaller and lighter, the frame has been significantly altered. It still uses a twin-spar configuration made of steel, but the steering geometry has been brought more in line with contemporary sportbikes. The ’91 CBR has a 25-degree rake and a 3.7inch trail, whereas the '90 model used 26 degrees and 4.3 inches. The fork stanchions have been bumped from 37mm to 41mm, and the fork now has spring-preload adjusters.

At the rear, a redesigned shock comes with rebound-damping adjustability, as well as seven spring-preload adjustments. RC30-type, 17inch wheels are mated to Michelin radiais, the 120/60-17 A59 front and the 160/60-17 M59 rear. Michelin has modified these tires specifically for the CBR. with changes in the profile for lighter steering. Wheelbase is 55.5 inches.

In keeping with the everything-ischanged theme, the CBR also gets new brakes all around. The 10.8-inch front discs are grabbed with revised, lightweight calipers. The front brake lever is adjustable, and the small master cylinder is borrowed from the Japanese domestic-market NC30, 400cc brother to the RC30.

Physically, the CBR is about the same size as before, though the ergonomics have been modified, with the distance between the seat and the handlebar shorter than before for less of a reach. It looks, however, as if the footpeg-to-seat distance may still be a little cramped.

If there was one area where the older CBR seemed most dated, it was its rounded styling that had gone basically unchanged since 1987. Honda claims the sharper, sleeker bodywork of the new bike is more aerodynamic than before, and that it offers better protection for the rider. That’s a bold statement given the efficient shape of the original machine.

If the new CBR does indeed pump out 100 horsepower, and is as slippery as Honda says, and weighs in close to the claimed 407 pounds, then the bike just may be the fastest 600 of all time—rumors of speeds in the 1 50-mph range have leaked out. And with its revised steering geometry, upgraded suspension and better tires, it ought to handle considerably better than it did before. All of which should have the competition heading for cover, as will the CBR’s $4998 price tag.

But we'll have to wait until we get a test CBR to know for sure. Then, we’ll have a much better idea of the machine’s capabilities. But for now, on paper at least, the CBR600 has the makings of a winner. 0