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Honda CB 400T III Hawk

 

 

 

 

Make Model

Honda CB 400T III Hawk

Year

1980-81

Engine

Air cooled, parallel twin cylinder, SOHC, 3 valve per cylinder

Capacity

395
Bore x Stroke 70.5 x 50.6mm
Compression Ratio 9.3:1

Induction

2x 32mm Keihin carbs

Ignition  /  Starting

CDI  / 

Max Power

43 hp @ 9500 rpm

Max Torque

3,4 kgf-m @ 8000 rpm

Transmission  /  Drive

6 Speed   /  chain

Front Suspension

Telescopic forks, 124.5mm wheel travel

Rear Suspension

Dual EVO dampers with 5-way spring preload adjustment. 96.5mm wheel travel

Front Brakes

Single 282mm disc

Rear Brakes

153mm Drum

Front Tyre

3.60 S19

Rear Tyre

4.10 S18

Wet-Weight

177 kg

Fuel Capacity 

13 Litres

Consumption  average

48.5 mp/g

Standing ¼ Mile  

14.2 sec / 88 mp/h

Top Speed

110 mp/h

Cycle World Road Test 1981

Last year when the 1980 Honda Hawk arrived we were both gratified and slightly disappointed. There had been rumors the Euro Hawk, with its rearset pegs, six speed transmission, sporty bars and extra horsepower, was at last destined for our shores. The grass-is-greener crowd of Europe watchers looked forward to a ja//y replacement for the earlier five-speed series, already known for fine performance, good handling and uninspired commuter bike styling.

When it got here, the 1980 Hawk did have a six-speed transmission and a welcome styling facelift (or tank and seatlift) from the 750F school of design. Missing, however, were the rearsets and low bars, and instead of delivering more performance the '80 Hawk actually lost a small bit of upper end power compared with the '79. More stringent EPA requirements had driven the old 32mm Keihin carbs into retirement in favor of a set of 30s with accelerator pumps and leaned out idle circuits.

F'iston and cylinder head shapes had also changed to prevent detonation on the-leaner needle, though the compression ratio remained the same at 9.3:1. Acceleration was better by a couple of tenths in the quarter mile, thanks largely to the six-speed transmission. But those who tried to road race the 1980 Hawk found that while it handled and had good throttle response, the bike developed a touch of asthma right at the upper end, where the loss of a few mph was critical. So the peg-scraping crowd held onto their '79 and earlier Hawks, lest they become fodder for all those Yamaha RDs.

These small differences in speed and power, of course, mattered little and  most versatile street bike in the class. It just wasn't quite as good,' from a sporting point of view, as we knew it could be. Once more the feeling lingered that people on the other side of the Atlantic were chugging down Chateau Lafite while we'd been served another glass of Cold Duck.

This year's rumor mill again had us unwrapping a new and better version of the Hawk, perhaps with a little more horsepower or even the fabled rear pegs/low bars option. After all, Honda sponsors a racing class strictly for Hawks in Europe and in Japan the bike is extremely popular for sporty riding and amateur road racing. A lot of people in the industry, we are told, ride Hawks on the street and in competition. Interest in the Hawk is high and so, in theory, feedback from all this enthusiasm influences the design of the new models.

Well, then. The new bike is here, and once again an undetermined percentage of this rumor, speculation and theory has proved correct. The 1981 400T is indeed an improved and reworked motorcycle. Not as radically redone as those of us who love to be astounded and amazed might have hoped, but altered for the better. There are no sweeping changes in tuning, horsepower or concept, but Honda has fed the Hawk into its legendary Attention to Detail Machine and a more refined product has rolled out the other end.

First, the big non-news is that the engine is unchanged, identical to last year's.
No return to bigger carbs, bolting in of tricker cams, etc. In spite of this, Honda suggested we might be surprised at how well the bike runs. If the engine is unchanged, we asked,- why should its performance surprise us? Don't expect anything spectacular, they said, just a Hawk that works at its full potential. It seems some special attention has been given the dies used for cylinder head casting, to ensure exact conformity to the dimensions of the original design. This is especially important at the exhaust ports, where small inaccuracies of shape can hurt combustion chamber scavenging and horsepower. No big thing, just a little industrial blueprinting, if you will.

Otherwise the engine is the same 395cc sohc counterbalanced vertical Twin offered last year. When testing bikes that have been around a few years it's easy to forget small details that made a machine special when it was introduced. And the Hawk's specialty is excellent combustion efficiency, which allows one of the world's mildest looking and sounding engines to produce respectable figures at the drag strip and on the dyno. The Hawk is the first mass-produced 400 four-stroke to come within shooting distance (and sometimes killing distance) of its two-stroke displacement rivals, and when introduced its performance also overshadowed that of Honda's own 400F.

Our 1981 bike ran through the quarter
mile in 14.28 sec. at 88.2 mph. That's just a hair quicker than last year's 14.29 sec. quarter and 1 mph slower This degree of performance variation can usually be attributed to barometric pressure, air temperature or the phases of the moon. Suffice it to say the motor works about the same as it did before. It's still the quickest and fastest 400 around, now that the RD400 has gone to its reward.

Blame for much of this liveliness can be pinned on the Hawk's cylinder head, which has a single cam running three valves per cylinder. One cam lobe opens two intake valves via a forked rocker arm, and another, slightly offset, rocker arm moves the single exhaust valve in each cylinder. The combustion chamber is of the wedged pentroof persuasion, the spark plug is offset and the piston is mildly domed with valve relief pockets. The two intake valves flow more air for their combined head area than a single large valve and also present less individual valve mass for the rockers to open and springs to close. This provides a better safety factor at high rpm, an important advantage with a highly oversquare (70.5mm bore and 50.6mm stroke) engine like the Hawk's, where maximum torque and power are made at the high end of the tach. Twins, unlike Fours, have no cylinder head width problems from highly oversquare bores.

The engine breathes through two 30-mm Keihin CV carbs with accelerator pumps. The choke button for the carbs is located between the handlebars; a good thing, because the Hawk is a bit cold blooded and the choke has to be reduced gradually over a long warmup period or the engine staggers at sudden throttle openings. The motor exhausts through a pair of double walled exhaust pipes and upswept mufflers, which are linked beneath the engine by Honda's patented Power Chamber, an extra muffling device. Twin twirling chain driven counterbalances (try saying that ten times after half a quart of Jack Daniel's) in the crankcase offset the vibration of the Hawk's 360° crankshaft throws, which have both pistons rising and falling together and firing on alternate strokes. Plugs are fired by breakerless CD ignition.

The most outwardly apparent revision in the 1981 Hawk is its styling. Street-corner bystanders and the uninitiated may not be astounded by glaring differences in the first Hawk that speeds past, but the 400T now shares its tank, seat and tail section with Europe's 400N model. The tank, which looks nearly unchanged from the side, is now wider at the front and tapers toward the rear, with slight knee indentations sculpted into the medal.

The front half of the seat is lower and firmer than before and the tail section has a spoiler upsweep in the style of the 750F. Our test bike was finished in bright silver, which looks a bit more lustrous and metallic than last year's version of the color, accented by bold stripes of black and dark blue. Someone somewhere probably hates the bike's looks, but we've yet to find anyone who thinks the Hawk isn't a very good looking motorcycle.
Capacity of the gas tank is unchanged at 3.4 gal. and its shape conforms better to the rider's knees with the tapered and cutaway rear section.

The tank can be a little tricky to fill at gas stations. Its flatness near the top of the filler neck makes the tank look full, when in fact another three or four tenths of a gallon can be squeezed in with some careful trigger work on the pump nozzle. There's a lot of capacity in that last inch of tank, and at the Hawk's 57 mpg you can shortchange yourself a few dozen miles at the pump. As a credit to Honda's production uniformity, our '81 bike got exactly the same mileage on our 100 mi. test loop, right to the tenth of a mile, as the '80 model.

The Hawk's seat is both lower and even harder than last year's, which hardly cried out for more firmness. The rider's portion of the seat feels like a real saddle, in the equestrian sense; it could be made of leather and stuffed with sawdust or ground hemp or whatever they stuff saddles with these days. It's Honda's entry in the Italian, no nonsense racing seat competition. It feels hard the moment you sit on it, and while it doesn't get a lot worse with passing time, you never quite forget it's there.

The seat also has a slight concave shape which gives you the uncomfortable sensation of sitting in a sling at times. (In our pendulum theory of improving the breed, we estimate the motorcycle world is only a few years away from rediscovering the flat, comfortable bench seat, along with those elegant, lightweight wire wheels we used to see.) Passengers on the rear portion of the seat reported no discomfort, even on medium-to-long rides.
With a lower saddle the footpegs, which have never been criticized for being back too far, feel even farther forward. This placement means the pegs have to be wide-set so the rider's feet can clear the clutch cover and engine cases. The bottom end of the Hawk motor is no model of narrowness for a vertical

Twin anyway, and it puts the Honda's footpegs nearly 3 in. farther apart than those on a Kawasaki 550, for instance. The new narrowness at the rear of the tank exaggerates the feeling of sitting in a wide-footed stance. The bike doesn't need radical rearsets, just a more reasonable rearward peg position.
But enough of this niggling over comfort. On to the good stuff. In addition to revised styling, the new Hawk has been treated to a whole R and D briefcaseload of mechanical improvement and subtle refinement. Much of this effort was aimed at the front end. The Hawk has a new disc
brake, a wider front wheel (2.15 in. replacing 1.85 in.) with reversed ComStar spokes, an air fork, and instruments that glow with translucent dials.

The front brake caliper is a dual piston design, shared this year by all the Hawk's big displacement brethren. Instead of a single large piston operating a square set of brake pads, the new caliper has two smaller pistons, side by side, squeezing a longer and narrower set of pads. The swept area on the rotor is actually reduced some from the old design, but the payoff comes from improved mechanical advantage, with more pressure exerted farther out on the rotor. A narrower band of swept area also makes it possible to lighten the inner section of the rotor with more holes, reducing unsprung weight by 2.5 lb. over last year's setup. A further bonus comes in better caliper rigidity. Because the two caliper arms don't have to reach as far, they flex less and reduce sponginess at the lever.

This juggling of brake physics works pretty well. The Hawk has a firm lever feel with a progressive effort/stopping power ratio. What you put into the lever you get out. Our braking distance of 132 ft. from 60 mph was about average for the class, and 3 ft. better than the old Hawk, but stopping power was limited somewhat by the front tire, which locked up for the last few feet of each brake run and lost some distance. One or two fingers, firmly laid to lever, were all it took to pull the front tire down to a smoking halt from most legal road speeds. The Hawk's rear brake, which was predictable and easily modulated, is a 5.5 in. drum which now has small cooling fins on its outer surface, like those on the CX500.

The Hawk has air-assisted forks this year. Softer springs, coupled with air adjustability, make it possible for the rider to pump in his own preferred spring rate for varied riding conditions. The air caps have a crossover tube for balance and a single filler valve on the right fork leg. The owner's manual recommends a pressure of 11 psi, plus/minus 3 psi. At 14 psi a considerable difference in ride stiffness is felt and the springs sack less than they do at normal atmospheric pressure. Even with pressure released from the fork, the Hawk doesn't feel overly mushy or dive excessively on braking. The ride is just softer and a small amount of ground clearance is lost.

A heftier upper triple clamp now holds the fork legs together, replacing the more stamped-out item from the past. The old one worked okay as long as the bolts were kept tight, but didn't look as though it should. The front wheel is wider while the rear remains the same, and both wheels get newly designed tubeless tires. Honda says the Hawk's new tires were designed for better stick and greater sidewall rigid-ity, to complement the generally stiffened front end.

There are finally drain plugs on the fork legs this year, a happy circumstance for those who like to change fork oil without disassembling the front end of the motorcycle. All of us, in short.
The Hawk now has VHD (Variable Hydraulic Damping) rear shocks instead of FVQ (Full Variable Quality) units. The VHDs still work on the principle that a hydraulic blow-off valve prevents the
shocks from pumping up or overheating when the rear suspension is overtaxed by hard, rapid movement. Quality control changes have been made, however, such as better chrome on the shaft and a one-piece shock body. Damping rates on the shocks are not adjustable, but the normal five preload adjustments are provided for the spring.
The Hawk's suspension and road manners were hard to fault last year, and Honda's concentration on the fine points for 1981 hasn't hurt its handling. Steering is neutral and agile around town, but as you pass that last block of condos at the edge of civilization and begin to pick up the pace on your favorite empty road, the feeling of stability and accuracy remains. The Hawk is another of those bikes from Japan, once rare and now becoming more the norm, that simply has no tricks up its structural sleeve. Pick an arc through a fast corner, throw the bike down to the footpeg and you can hold it there until the road goes straight. No surprises, no unseemly midcorner waltzing between the frame and back wheel, and not a trace of cold sweat to soak the riding gear of the enthusiastic rider. The Hawk goes where directed without resistance. Improvements on the '81 enhance that feeling of solidity and the air caps give some latitude in adjusting suspension compliance as well as ride height.

The Hawk's only real shortcoming in fast riding is cornering clearance, which is not all it could be for a vertical Twin. The aforementioned wide pegs mean that the brake lever also sticks out more than necessary, as anyone who roadraces a Hawk will tell you, and hard righthanders can smack the lever firmly into the pavement. Dragging footpegs, of course, are a useful early warning system on street bikes, telling you where the tire is relative to the pavement, but the Hawk could get away with slightly better clearance. To fulfill its promise as a sporting motorcycle the Hawk needs its footpegs moved back and inward and the brake pedal and exhaust pipes tucked closer to the frame.

Another occasional glitch in the Hawk's happy running is its shift action, which felt decidedly notchy and stiff on our test bike. A lot of pedal effort is needed during rapid downshifts at stoplights. We attributed some of the stiffness to a new bike, but it showed no sign of loosening up as we put on more miles. Another in-town irritant is the side stand.

The stand has a nice big tab that makes it easy to operate, but the tab is back farther than on most bikes. So when you come to a stop you reach back with your foot and paw the air for a tab of metal that isn't there, or at least isn't where you expect it to be. Not a big problem, certainly, but everyone who rode the bike mentioned it.

Rounding out its numerous refinements, the Hawk has new instruments this year. The tach and speedometer faces have translucent numbers, lighted from beneath, so the dials can be easily read at night without casting a distracting glare into the rider's eyes. Unfortunately, the trip odometer doesn't get quite as much light as it needs and is a little hard to read. The instruments are not the most accurate we've tested. While the speedometer tested only 2.5 mph low at 60 mph when run through the drag strip clocks, the tach was way off. Our gearing information and rear tire measurement indicate the engine should be turning 5455 rpm at 60 mph, but the tach reads about 6250, or an error of 850 rpm. At least people won't be over-revving their engines at redline. Even 5455 rpm is fairly busy on the open road at 60 mph, and we wish sixth gear on the Hawk's gearbox were just a little taller. The owner, of course, can always raise overall gearing with a larger countershaft sprocket if he wishes.

To put the Hawk in its proper evolutionary place then, you could say that 1981 is the year the 400T got nicer styling, better brakes, an air fork and a worse seat. With some good competition breathing down its neck, the Hawk is still the best thing going in its class, not by any single extravagant virtue, but as the well rounded sum of its own parts. The Hawk engine starts and, when warm, runs well. It puts out good broad power for its size and doesn't break. It performs and handles well enough to be a contender in road races, yet chuffs around town or idles in the driveway with all the snarling ferocity of a midsize family station wagon. It's a bike that, on demand, can be different things for a lot of different people, and for that reason

Honda will probably continue to sell a lot of them. There are a few compromises engineered into this universal appeal, but not enough to discourage any one segment of its market. Overall, the Hawk represents exactly what Honda is very good at, and that is setting a standard, getting it right, and then keeping it that way.

Source Cycle World 1981

 

 

 

NOTE: Any correction or more information on these motorcycles will kindly be appreciated, Some country's motorcycle specifications can be different to motorcyclespecs.co.za. Confirm with your motorcycle dealer before ordering any parts or spares. Any objections to articles or photos placed on motorcyclespecs.co.za will be removed upon request.  

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