Cycle News - Archive Issues - 1970's

with- ·J a 'look' . tha t ' sc r e a m s "FUNCTION" at all observers. Inspired by the instruments found in aircraft cockpits, the h uge , stark speedometer and tachometer feature non- glare glass (formerly available only on BMWs), orange numbers on black faces, and white-tipped. thick orange needles. At night, the speedometer needle glows with illumination refracted from the odometer and resettable trip meter dial lights. Each control module is mounted on forged aluminum , I·beam construction . adjustable handlebars which clip to the tops of the fork tubes. The orange hom button on the left bar is ' the largest th is side of an automobile steering wheel hub . and can be found easily and quickly even when the rider's hands are heavily gloved against cold weather. The tum signal and high/low beam control switches are large , each unusually shaped like a flattened. serrated "U." Control indicator lights are set into the speedometer/tachometer mount pla te. flat plastic lenses with their functions lettered on their faces. Each light is too bright. the only distracting flaws in an otherwise fine control group. On the street and at the racetrack . the CBX's obvious technology.upstages its potential function for the first-time viewer . but the unseen . internal technology is far more impressive . Consider the effort expended to keep the weight down as low as possible. at least on this prototype. The front and rear fenders are both plastic. as is the seat base. The handlebars and footpegs are forged aluminum. The Com-Star wheels are all- aluminum and carry tubeless tires . The clutch is aluminum . the camshafts are hollow. and the shift linkage cover. countershaft sprocket cover. alternator case and cover . and oil-pump pick u p casing are ' all magnesium. The wet sump engine avoids the need for a heavy re mote oil tank and lines. but necessitates the use of a small oil cooler mounted ahead of and a bove the cylinder head . in conjunction with a second oil pump secti on to supply the cooler. T he engine it~lf took lrimajiri just o ne-a nd -a -hal f years to d esign completely. The grou ndwor k was a ll laid a decade ago with his sm aller road racing sixes and a lso a couple of Formula O ne ca r engi nes that he design ed . Each cylinder has four valves. two 25mm intake va lves, two 22mm exhaust valves . Four small valves are each lighter than two la rge valves. Lighter valves are more easily kept under control at high rpm . More control means less chance of valve floating . and less chance that the valve-adjusting shims. which sit atop recessed tappets . will be spit out at high engine speeds. Valve angle is 25° • intake valve lift is 8.3mm and exhaust valve lift is 7.5m m . Intake valves open 5° BTDC and close 40° A BD C . Exhaust ' va lves ' ope n- 40° -BBDC and ' close 5° ATDC . Each Stellite-faced valve is held against its sintered iro n seat by double , inner-outer valve springs. The valves are opened by dual overhead. castiron , hollow camshafts. To avoid heattreating warpage. each camshaft is actually made of two pieces . joined at the center by an Oldham coupling. A 9.5mm Hy - Vo chain drives the exhaust cam from the crankshaft. and another 9.5mm Hy -Vo chain drives the intake cam from the exhaust cam. Each has its own spring tensioner, The combustion chambers are conventional with five-faceted roofs . looking like they came right out of an XL250. Like the cylinder head and cam cover. the cylinder is a single sand casting. Liners are iron with cylinder centers 82mm apart and 64.5mm bore. There is room to accommodate overbore liners for a displacement increase to about I200cc. The CBX uses three -ring, flattopped pistons. connecting rods of f!?rged steel with plain bearing big ends and a one-piece, seven -main bearing crankshaft. Piston stroke is 53.4mm. At least one piece of unused technology is perhaps more intriguing than the technology actually used. The Honda engineers knew from the start that the six- cylinder engine produced an exciting exhaust note . They also knew that Honda wanted the C BX to be a jet-fast , startling motorcycle to slap aside the company's recent dull . drab street bike image. So. a group of sound engineers went to a Japanese air force base and taped Phantom jet fighters taking off and landing. After days of tape recording. they returned to their research facility and built an exhaust system that made the CBX sound just like a Phanton jet. The noise level was within legal limits. but the sound itself had an intensity even Honda's top engineers find hard to explain. One said that the sound made the rider feel as if he were traveling at 200 mph at an act ual 100 m ph. In the end. the Honda honchos decid ed against b uilding mo torcycles whic h sound like jet fig h ters. but the very th ought that such a thing could be b uilt at all is staggering . . Even without t he jet-sound exhaust. the prototype Honda CBX is the mos t exciting street m otorcycle ever . Bu t since no one . except perhaps Honda test riders) . has 'ridden a production C BX . one can only speculate on how well the bike will fare in the transition from the tool room to the production line . Soon . the largest monthly motorcycle magazine in the United States will present to its readers the "exclusive. first test " of the CBX . - without noting that the machine tested was hand built. Like the editors of that magazine. we can only hope that the essential endearing qualities of the prototype CBX survive the long trek to the dealer showrooms of America. • Specifications Honda CBX Super Span Bore x stroke ••.••. . . .. ... .• .••..• .•........•. . . .. • • 64.5 x 53.4mm Displacement 1047cc Compression ratio . •.. . ...... . • . . . ..... . .. . . . . . ... . .. . ... . . . . 9.3:1 Oil capacity •. . .••..•.• ... . ... .••.• •.•. .... .•• ..• . ... ... .••. 5.8 qt. Wheelbase ... • . . • •. .. .. .... . .. .... ... . •. ... . ...... •. . •. . . • 58.9 in . Rake/trail•. . . . . • . . . . .. . .. ..• .. .. .. . . . ... . . .. .•.• . . • • . . • . 27° /4.7 in. Seat height 32 in. Ground clearance . • •.... •. ••. .. .•. . • . . •. : 6 in . Weight with fuel. • . . • • • • . • • . . . . • . • . . . . . . . . . . • . . . . . . . . . . . • • . 600 lb. Front tire. . . . . . . . . • . . • . . • . . • . • • . . . . . . . • . . . .. • . 3.50 x 19 Dunlop F11 Rear tire 4.25 x 18 Dunlop K127 Fuel tank capacity. . • • . • • • • . • . . • • . • . . • . • • . . . . . • • . . . . • . . . . . . 5.3 gal . Peak Horsepower ••.•. . •.. •• '. • • . •. . . • . . 85.6 @ 9000 rpm. rear wheel Peak torque . . . . . . .. . . . . .. . . . . . . • .• 52 ft./lbs @ 8000 rpm. rear wheel Top speed 136 mph @ 9500 rpm Average gas mileage 35 mpg Release date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. April 1978 Tu beless tires. smooth styling. dual front disc brakes and simple. functional ins truments round out the prototype package Honda CBX six cy linder. 9

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