Cycle News - Archive Issues - 1990's

The CBR1100's heart T o extract a claimed 162 horsepower from the CBRllOOXX's powerplant required more than just a makeover of either the CBRlOOO or CBR900RR's engines.The XX's engine is all-new, although it would be fair to say that it combines much of the technology learned through the construction of the aforementioned powerplants, along wiJh the engine of the CBR600. The XX's engine is canted forward by an additional 22 degrees compared to the CBRlOOO, while the included valve angle has been reduced from 32 degrees, as found in the CBR600/900, to 30 degrees. Valve actuation is by bucket and shim, and attention to mass minimization has seet:l 22 pounds .shaved from the CBRlOOO's engine, even though the XX sports an extra 140cc and a unique dual-balance-shaft design. . Th~ latter has two benefits: the v:irtual elimination of high-freqUency VIbration - and, due to that, the ability to use the engine as a stressed member of the frame. To eliminate vibration, many manufacturers rubbe.-mount their engines, which then requires the frame to be made stiffer (and heavier). The XX solves both these dilemmas with its dual-balance-shaft design. which features one balancer gear-driven off the front of the crankshaft and the second driven off an idler gear above the crankshaft. The XX's liquid-eooled DOHC 16-valve four has bore and stroke dimensions of 79 x 58mm for a capacity of 1137cc, with a compression ratio of 11:1 and D-shaped ports similar in design to those. found on the HRC heads normally reserved for the likes of factory RC30s and RC45s. Honda claims 162 horsepower at 10,000 rpm and torque of 91.9 footpounds at 7250 rpm. Ignition is handled by a computer-controlled three-dimensional mapped unit similar to that on the '96 CBR9OQRR, with sensorS that monitor throttle angle and engine speed. Similarly, the bank of four 42mm flat-slide CV carbs is similar in design to the CBR9OORR's carbs (with throttle-position sensor mentioned above). The altema.tor is mounted on the left-hand end of the crankshaft to allow room within the crankcases for the two balance shafts. However, engine width is not compromised - the narrower spacing of the XX's Cylinder Block Comparison ClR1100XX cylinders and the side-mounted cam chain has allowed the cylinder block to be substantially downsized over that of the CBRl000. Cooling duties are handled by a large aluminum radiator with an oil cooler mounted below the steering stem and fed by air through the two . slots under the headlight. Honda's engineers have paid particular attention to noise reduction, with the clutch cover floating On a rubber gasket and the primary drive gear using a spring-loaded "scissor-type" arrangement to dampen backlash. Keeping exhaust noise in meck is the 4-2-1-2 system, which has stainless-steel mufflers and a painted steel header section. . The CBRllOOXX doesn't sport a .ram-air system, but has its cool mtake all routed into a large 9.S-liter airbox via the fairing's front opening. This is further aided by a "ceiling panel" which isolates the intake ail: from the heat given off by the radiator and engine. This divider panel combines with the cockpit panels to create a large cool-air extension "reservoir" to the airbox, with two large-capacity ducts draWing the XX's intake air from this area. The two vents under the headlight play no part in the XX's intake. With a claimed 162 horsepower on tap, Honda's engineers decided that. there was no need for the addition of a ram-air system, despite haVing such a system on the CBR600. However, one can't help but imagine that should a rival manufacturer try to outdo the XX, the Honda wizards simply will bolt in some panels and find another 10-15 . horsepower. Now there's a frightening thought. Engine Size Comparison CBR1000F ~ U is at 10,500 rpm (a theoretical top speed of 195.3 mph). I have to admit to being impressed by the seamless spread of power of the XX's engine. Not only will it commute "timidly" at the aforementioned 2000 rpm, but it'll spin effortlessly through to the 11,500 rpm rev limiter - something I found quite often around the 3.59-mile . track. There's no shortage of breath up top on the Honda, even if the backroom boys have decided against ram-air (at least for now). ON TRACK For a comfortable, user-friendly, sport-touring road bike, the XX's ability around Paul Ricard was impressive. That "twitchiness" which I mentioned earlier could be put down to two areas. Firstly, at 490.6 pounds, it's still a big bike to throw around at racing speeds - the Yamaha is 55 pounds lighter, and the CBR900RR is n~arly 84 pounds less porky. Riding around at breakneck speeds on compliant suspension tuned for the road didn't do the XX any favors when it was getting flung into comers at riciculous velocities. That the bike is so forgiving and tolerant of fools is a huge feather in its cap. I remember one particular "moment" when I barreled into the S de la Verrerie along the shorter front straight and dug the left footpeg into the bitumen. The Built to fly_ _ W it~~t a d~bt, the most striking. aspect of the CBRllOO is its faJI10g deslgll. Oean aerodynazmcs were at the top of the list, . and there can be no doubt that the bullet-shaped nose and the twlD stacked headlights will create plenty of discussion. So, too, will the color options. All three variants are somewhat understated with decals and graphics kept to a minimum. The bike comes in three color options: titanium metallic (as on the test bike), mute black metallic and candy muthos magenta. Honda's claims for the XX's aeroAir Intake Row dynamiC effiCiency are impressive, with a Cd figure better than Honda's own NSR250 racer-replica. In fact, according to Honda, the frontal area of the XX is equivalent to that of the average 50cc motorcycle. One of the problem areas Honda's stylists attacked was the headlight placement, which traditionally has required a blunt frontal area to accommodate the light(s). With the need to taper the nose of the fairing to a bullet-shaped point for aerodynamic reasons, the XX's novel "piggyback" headlight was developed. The separate low and high beam units are each lit by a 55-watt bulb, with Honda dubbing its innovation a "free-form, multi-curvature reflector design." It offers nearly twice the brightness of a conventional dual-bulb light of the same wattage, according to Honda. 'But the aerodynamic wizards didn't rest with just the headliShl The frontal area of the XX was designed with the fairing opening tapering behind the front w1;leel to give the smallest possible opetUng while still XX didn't even twitch, although as the BT57s were "unloaded," the whole bike drifted across the circuit. At that point, the XX was doing around 115 mph. The 500cc GP bikes don't even use that part of the circuit, peeling right before then to utilize the "short" circuit, which cuts out a third of the' Mistral Straight as well. Wimps... EN GARDE DEUX CHEVAUX It was on the public-road loop through the surrounding hills that the -Honda really impressed, however. Lap after lap of redUne speeds on the track had masked the XX's midrange punch, but twisting the throttle on public roads . soon put the bike's performance in perspective. Want to' overtake that Citroen 2CV blocking yoUr lane? Don't bother changing gears if you've got at least 2000 rpm on the tacho - just hang on tight. . For the record, the gearbox isn't as smooth shifting as I've come to· expect of Hondas of late, although the slight clunkiness didn't lead to any missed shifts or false neutrals. As long as I was positive with my foot movement, then the gearbox was likewise. The seating position is excellent, with rto strain on the wrists and good projection from the fairing, And I should know about the latter, as it rained les chats and les chiens for the second half of my battle with errant Pugs and R5s. In fact, the hazardous conditions really allowed the XX to shine - like the diesel-stained roads. It was the first rain in southern France for over two weeks, so the blacktop was somewhat slimy. I'll admiJ up front that I had my doubts about the linked brake system at the race track. Just using the front lever caused no ill effects, but dabbing the rear as well ~ warp velocities when braking hard into the apex would unsettle the bike. . That is where the second part of the XX's "twitchiness" comes in (mentioned about six paragraphs ago), with the repertoire on "normal" brake setups.. To be fair, braking hard in a straight line at the track using the front lever with minimal rear pedal had the bike shedding allowing adequate air for cooling. There are no broad engine surfaces to . act as a windsock on this baby. The fairing itself fealures a reduced number of body panels to give a c1earier look (with fewer fasteners to disturb the ail: flow), although the downside of this is that in the case of a tumble, it won't be possible just to replace.a smaJl damaged paneL as the damage will be part of a much larger component. . . Many of the fairing panels have been formed using gas-assist injection pioneered in the constlmer-electronics industry. This allows fo'r thinner but stronger panels, which means less weight and less bracketing. but also panels that don't flex as much. The fasteners for the fairing panels are small and flush-fitting. taking the aerodynamic component of the XX a step further. Another item to cop the windtunnel treatment is the front fender, which features a long nose, deep side valances and two ducts that assist high-speed stability. At high speed, these ducts create a low-pressure zone on the upper surface that draws jets of air up from under the fender, countering the wind's effect on the front wheel. Like the fa.iring panels, the fender is molded using gas-assist 'injection to provide a rigid "fork brace." Even the front tum indicators have been moved from the fairing sides to the mirror pods to improve the wind-eheating ability of the CBR. Thankfu1ly, the mirrors stick out far enough and are large enough to be more than just cosmetic add-ons. With the deceptive mile-munching ability of the CBRll00xx. it will pay to keep a wary eye out for flashing red lights. .

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