Honda CBX400F

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Honda CBX400F
Also called CBX 400 F
Production 1981 - 1983
Class Standard
Four stroke, transverse four cylinder. DOHC, 4 valve per cylinder
Compression ratio 9.8:1
Horsepower 48.01 HP (35.8 KW) @ 10500RPM
Fuel System 4x26mm Keihin carburetors
Ignition CDI
Transmission 6 Speed
Suspension Front: 35mm Kayaba forks
Rear: Single air shock
Brakes Front: Single 229mm disc
Rear: Single 229mm disc
Front Tire 3.60-H18
Rear Tire 4.10-H18
Wheelbase 54.29 inches (1379 mm)
Length 81.1 inches (2060 mm)
Width 28.31 inches (719 mm)
Seat Height 30.71 inches (780 mm)
Weight 138 kg / 304.4 lbs (dry), 151.0 kg (wet)
Recommended Oil Honda GN4 10W-40
Fuel Capacity 18 Liters / 4.7 US gal
Manuals Service Manual

The Honda CBX 400F was an Air cooled, four stroke, transverse four cylinder, DOHC, 4 valve per cylinder Naked motorcycle produced by Honda between 1981 and 1982. Claimed horsepower was 48.01 HP (35.8 KW) @ 10500 RPM.

Engine[edit | edit source]

The engine was an Air cooled cooled Four stroke, transverse four cylinder. DOHC, 4 valve per cylinder. The engine featured a 9.8:1 compression ratio.

Chassis[edit | edit source]

It came with a 3.60 H18 front tire and a 4.10 H18 rear tire. Stopping was achieved via Single 229mm disc in the front and a Single 229mm disc in the rear. The front suspension was a 35mm Kayaba forks while the rear was equipped with a Single air shock. The CBX400F was fitted with a 18 Liters / 4.7 US gal fuel tank. The bike weighed just 138 kg / 304.4 lbs.

1981 - 1985 Honda CBX 400F[edit | edit source]

The Honda CBX 400F model is a Naked bike. In this version sold from year 2006 , the dry weight is 138 kg (304.2 pounds) and it is equiped with a Single cylinder, four-stroke motor. The engine produces a maximum peak output power of 48.00 HP (35.7 kW) @ 10500 RPM.

1982 Honda CBX 400F[edit | edit source]

Manufactured in the 80's, the CBX 400F had an air cooled, four stroke, transverse four cylinder, DOHC, 4 valve per cylinder, 399cc engine which was able to develop 48 horsepower at 10500rpm.

Overview[edit | edit source]

It's not easy to follow in the footsteps of a legend. Not even a junior-grade motorcycle legend like Honda's CB400F. Its half-life on this planet was so brief that its biography is but a short paragraph in the magnum opus of moto-history, yet it still managed to earn cultbike status amongst the cafe-crazies. Many of them even vowed never to forgive Honda—not only for terminating a magnificent motorcycle after just three short model years (1975 through 1977), but for having the gall to think that the CB400 Hawk, a twin-cylinder econobike, would be a suitable replacement.

Well, listen up, all you fans of the late, great CB400F: The 400 Four is back. No, it's not the same CB400F you've grown to know and love, it's a substantially better one—better in power, in handling, in braking, in comfort and in just about any other way you can imagine ... except for availability. The catch, you see, is that this bike, called the CBX400F, is sold only in Japan. And American Honda professes to have no intention whatsoever of bringing it into this country. Not now, not ever. And for the same reasons that sent the original CB400F down the tubes: It's so costly to manufacture that it can't be competitively priced, and the target audience is felt to be too small to satisfy Honda's minimum sales-volume requirements.

That's probably okay with you, though, since most riders didn't lament the passing of the old 400 Four any more than they do the new one's failure to reach these shores. They are, after all, only 400s, which equates to buzzy, twitchy, cramped, slow, little motorcycles, the kinds of bikes in which you have absolutely no interest. But before you turn a deaf ear, hear this:

The CBX400F is none of those things. We know; we spent an entire month testing one that had been imported by DG Performance Accessories of Anaheim, California. And we're talking about a mid-13-second motorcycle here, folks, a bike that'll blow not only the old CB400F into the weeds, but a lot of bigger and more highly exalted machinery as well. We're talking about a bike that weighs just 402 pounds and has a low, 30.7-inch seat but that doesn't feel at all undersized; a motorcycle that will dart off into a fast corner at the very thought of turning, yet is as stable on the open road as something twice its size. We're talking about an honest-to-God, for-real motorcycle that just might, if you could get your hands on one, make you forget that the original 400 Four ever existed.

Your first indication of the CBX400F's for-realness can be found on the tachometer face, where the engine redline is set at an unbelievable 11,500 rpm. Jeezus. Nothing but purebred racing machinery has ever had a redline that high, especially a four-stroke. But Honda has struck the mother lode of rpm on this bike without resorting to anything but its tried-and-proven short-stroke, four-valves-per-cylinder technology. The sizable bore of the highly oversquare engine (55mm bore and 42mm stroke, as opposed to the 51mm by 50mm dimensions of the CB400F) provides the large valve area needed for a high power output, while the extremely small and light valves in each 99.8cc cylinder permit ultra-high rpm. And the short stroke yields the low piston speeds necessary to prevent the engine from ripping itself apart at redline.

Indeed, but your mental tachometer just isn't calibrated to deal with 11500 rpm, so you'd never know that the engine wasn't self-destructing by the way it sounds at those speeds. The CBX400F wails like a runaway air-raid siren as the engine approaches redline, and the shrieking resonates inside your helmet so loudly that it's all you can hear. The intake roar alone is menacing enough, as though you and the seat are about to be sucked into the 26mm Keihin CV carbs at any second. And you can't help but feel that something—a piston, a rod, perhaps one of the 16 valves that is being hammered open almost 100 times a second—is going to come flying up and eunuchize you on the spot.

Of course, this all sounds more apocalyptic than it really is, since the CBX400F is perfectly happy to run all day in these absurd rpm ranges. What is surprising though, is that despite the engine's high rpm inclinations, it's not at all peaky.

The best performance, obviously, comes in the upper part of the powerband, say, between 7500 rpm and redline. And to that end, the slick-shifting six-speed gearbox has very closely spaced ratios that keep the revs from dipping below nine grand (except between first and second, where they drop from 11,500 to about 8000) during a WFO run. Nonetheless, the power delivery is almost linear from idle to redline, with only a slight increase in acceleration in the upper third of the rpm range.

Some of the CBX400F's reasonable mid-range stems from the exhaust system, which pairs off the cylinders that fire at even, 360-degree intervals (Nos. 1 and 4 lead—^ into the left muffler, Nos. 2 and 3 into the right). The conventional arrangement (feeding Nos. 1 and 2 into the left mufflejtf^ and Nos. 3 and 4 into the right) is cos- -metically more symmetrical but not as efficient, since it adjoins cylinders that fire at uneven (180/540-degree) intervals.

This is not to imply that the CBX400F's midrange performance is in the literbike league; it's not. There's usable power on tap at virtually all rpm in all gears, probably even more so than on the old 400F. But when you're at cruising rpm and want to summon some serious acceleration, a downshift or three usually is in order. If that's the trade-off for having a 400 that performs with the excitement of this one, it's a small price to pay. Honda claims a whopping 48 horsepower at 11,000 rpm for this engine, which is more than 10 horses and 1500 rpm higher than on the CB400F. But since the new bike's 13.588 quarter-mile time is 1.2 seconds quicker than the old one's, we have no reason to doubt that claim.

Those dragstrip numbers also mean that the CBX400F will outrun a slew of 500-550cc motorcycles and all of the 400-450cc four-stroke twins. And any stock RD400 Yamaha that sees a CBX400F coming had better run the other way if it hopes to avoid being embarrassed.  Not that this racy, rpm-aplenty double-hammer doesn't have its practical side. For one, it's the first four-valve-per-cylinder fconda multi to abandon shim-type cam followers in favor of the forked, screw-adjustable type (a la Suzuki GS750E/ 1100E) that makes valve-lash adjustment easy and inexpensive. And everything else inside the engine is conventional fare, from the plain-bearing crankshaft to the Hy-Vo-type cam chain and primary chain to the solid-state breakerless ignition. The CBX400F engine might perform like a racer out on the road, but it's just another motor in the shop.

The same can be said about the chassis, which has a distinctly racy personality when in motion but is comprised mostly of ideas that have seen service on other Honda models. The front fork is air-assisted, as is the single rear shock that is Pro-Linked to an absolutely gorgeous cast-aluminum swingarm.

There are no provisions for making damping adjustments at either end—perhaps a concession to the inordinate high cost of a 400cc four but you will find one of Honda's TRAC anti-dive mechanisms on the left fork-slider leg. The steering geometry on the double-down-tube frame is a touch slower than the old 400F's (97mm of trail compared with 84mm), and the wheelbase is about an inch longer. Both tires are H-rated 18-inchers mounted on attractive ComStar wheels. See? Nothing revolutionary about that.

But due to the CBX400F's light weight and well-balanced chassis design, all of its handling magic is found in the riding, not on the spec sheet. The bike is so inherently stable that you don't have to concentrate on keeping it going straight when you're not turning, yet it practically begs to be tossed into a hard turn. It banks over with remarkable ease, even when braking hard, and it willingly follows whichever line you choose. You can even change lines in mid-corner if you so desire—partly because the steering remains so neutral when the horizon is tilted over at crazy angles, and partly because there's so much cornering clearance that you can usually tighten up your arc if need be. You have to lean this machine way, way over before the centerstand feet (and, on the right, the footpeg) contact the ground. Even with no air at all in the suspension units (not, incidentally, a recommended procedure), it takes a fairly aggressive charge through a corner (or a sizable bump therein) before hardware kisses highway.

Overall, the CBX400F handles corners of all sizes, shapes and speeds with aplomb, never wiggling or twitching in the least. But the bike has its finest hour in the tight twisties, where the quick steering and high-rev- s ving engine rocket it from i turn to turn about as fast as g most riders care to go. If you | don't come away from an £ llVfe-grand charge through * the hairpins on a CBX400F feeling like a card-carrying roadracer, chances are you never will.

Still, given its propensity for back-road blitzing, the Honda is quite comfortable in cruise mode. The engine is pleasantly smooth below 6000 rpm and acceptably so above it, and the ride quality most of the time is just short of plush. Only certain small, abrupt bumps deliver any harshness to the rider, and even some of those jolts would prove less annoying if the seat were more comfortable. It's rather firm and ill-fitted to the nether regions, rendering it a not particularly luxurious place to park for more than an hour or two. It's tempting to dismiss the seat's problems as merely the result of the bike being tailored for a 5-foot 5,130-pound Japanese and not for the average (five-ten, 170 pounds) American; but there's nothing elsewhere in the ergonomics to back that supposition.

The riding position offers a near-perfect Euro-style sportbike tri-angulation, even for six-footers, and the spacing between the rearset pegs and the foot controls seems spot-on for Amercian (read: big) feet. And a large rider can even see what he's left behind, since the mirrors are spaced fairly far apart, despite being mounted on narrowish, cast-aluminum clip-on bars. A rider of any size, though, can appreciate the most innovative feature on the entire machine: the brakes. Fundamentally, they're conventional ventilated-rotor hydraulic disc brakes, one per wheel, the difference being that each disc is enclosed within a housing reminiscent of a drum-brake hub.

The claimed advantages are: 1) The disc is protected from water and grime that could adversely affect braking; 2) the disc attaches to the hub around its outside diameter rather than around the inside, thereby dissipating heat more efficiently into the large, finned hub and not through the wheel-bearing area; and 3) attaching the disc around the outside allows both disc and caliper to be located closer to the cen-terline of the wheel so that their weight is more evenly distributed on the axle.

Unfortunately, it never rained during our test of the CBX400F, so we can't report on the bike's wet-weather braking competence. But we can tell you that in the dry^jk the brakes are superb. They're always won" Jf derfully progressive, sufficiently powerful and resistant to fade even when deliber4|J ately abused. Assisted by the TRAC-which, on this bike, works far better than any anti-dive on any motorcycle we've ever tested-the CBX400F's stoppability is above reproach.

The brakes are eye-catchers, as well, with generous finning on the hubs and calipers that gives them a high-tech, exotic ook. It's all part of a concerted effort by onda to style the CBX400F as a serious enthusiast's motorcycle, not as an entry-evel tiddler. It certainly works, to our eyes, at least. And the best styling lick of all is the rear turnsignals, which are cleverly integrated into the outer ends of the taillight lens. But since that places the signal lights too close together to comply with U.S. regulations, don't look for similar treatments on Hondas sold here.

That's too bad. The real pity, though, is that the entire bike, or anything like it, won't be sold here. It's our loss, since the CBX-model 400F is an exciting, competent, complete motorcycle, one whose only faults are its seat, its lack of small-bump suspension compliance and its mild shortage of rebound damping in the rear shock-all of which undoubtedly would be rectified once the bike were recalibrated for American roads and riders. Honda says that won't happen, but maybe it's time for all of us to reassess bikes like this one. Times do change, and the cli- mate for a 400cc, four-stroke, four-cylinder pure sportbike could be considerably healthier now than it was five years ago.

The CB400F got lost in the shuffle back then amidst everyone's mad rush for 11-sec-ond performance and hot-rod literbikes, but the pendulum has begun to swing the other way. The trend now is more toward mid-size motorcycles, and the CBX400F more than qualifies as one of those. Modern technology allows it to perform like a 550 and, in fact, almost as well as a CB750 Honda of the '75-'77 era. Besides, what endeared the original CB400F to its followers was its appearance more than its performance, for it was the first Japanese motorcycle that didn't look like one. But beneath its European-inspired cafe-racer exterior was little more than an overbored 1974 CB350 Four—certainly not one of history's most memorable motorcycles. But you have our guarantee that, given the chance, you would remember the CBX400F. And not just for its styling, either. It's one bike capable of performing like a legend as well as looking like one. •

Ride Review

• Okay, the CBX400F is unobtanium, but this isn't going to be another dissertation on how the motorcycles are always better on the other side of The Pond. That's almost incidental. But central to the 400F's attraction is that you can wring the be-jeezus out of the thing—going really fast in the bargain—and get off feeling that you've used every ounce of performance that the littlest CBX has to offer.

All that might not mean very much if the CBX were "just another 400." But it isn't. From the inboard discs to 16 of the tiniest valves you've ever seen, the CBX fairly sweats performance. And it all works. So you can view the CBX as just another interesting piece of hardware that's not available in stores if you want to. Not me. I figure that it's rolling proof that performance 400s—a class almost forgotten of late—still provide their own special joys. —Larry Works

• As a former owner of Honda 305 and 350cc twins, I've got a soft spot for small bikes. My roots run deeper, too, having spent most of my roadrace days aboard Yamaha RD350s and 400s. So riding the CBX400 was like meeting an old friend. While, the engine's broad powerband helped pump my adrenaline quicker, it was the chassis and brakes that made me rediscover sub-500cc riding. Specifically, the front disc and anti-dive fork retapped my small-bike energy, and most of my CBX-fun was doing Eye-Openers: slamming into corners with a handful of brake. It's a game that's especially fun on the CBX400 because there's no transition period while waiting for the suspension to settle before apex-aiming. And as any small-bike enthusiast will testify, that's the thrill of sub-500 riding. —Dain Gingerelli

• After my first ride on the CBX400F, I was not overwhelmed. Oh, it seemed to be a nice enough motorcycle, but it didn't feel nearly as fast nor as nimble as my much-modified '75 400 Super Sport. But then I went out on my 400F, and the rosy memories turned sour. The CBX400F is more competent in almost every way than mine ever thought about being. The new 400F revs quicker, turns with less effort, and has a better seating position and more power. The only thing I preferred on mine were the brakes, which have more feel, but at the expense of requiring more effort. There is one thing they have in common, though: Both 400s make willing accomplices for the sporting rider, allowing him to learn and improve his craft without scaring himself. Now, if Honda would only bring it here ....

Source Cycle Guide 1982

Make Model Honda CBX 400F
Year 1981-83
Engine Type Four stroke, transverse four cylinder. DOHC, 4 valve per cylinder
Displacement 399 cc / 24.3 cu-in
Bore X Stroke 55 x 42 mm
Cooling System Air cooled
Compression 9.8:1
Induction 4x 26mm Keihin
Ignition CDI
Starting Electric
Max Power 48 hp / 35.7 kW @ 10500 rpm
Transmission 6 Speed
Final Drive Chain
Front Suspension 35mm Kayaba forks
Front Wheel Travel 138 mm / 4.4 in
Rear Suspension Single air shock
Rear Wheel Travel 103 mm / 4.0 in
Front Brakes Single 229mm disc
Rear Brakes Single 229mm disc
Front Tire 3.60 H18
Rear Tire 4.10 H18
Dry Weight 138 kg / 304.4 lbs
Fuel Capacity 18 Liters / 4.7 US gal
Consumption Average 46 mpg
Standing ¼ Mile 13.5 sec / 155 km/h