Suzuki GSX 1100SX Katana

Road Test

It takes some getting used to, the radical styling, the humpback tank, the two-tone seat, the clip-on handlebars, the rearset footpegs. In the seas of imported motorcycles flooding the U.S., the original 1982 Katana looked different and functioned more like an exotic Italian sports bike than a product of industrial Japan. The Katana made no concession to middle-of-the-road and shunned the rider interested in comfortable seating and compliant suspension. Its wild looks, its wind-cheating aerodynamics (which gave it, despite just 998cc, the highest half-mile speed of any stock motorcycle tested by Cycle World in 1982) appealed to hard-core performance enthusiasts.

Why a 998cc Katana? Because at the time the Katana was developed, Suzuki's latest 1074cc four-valves-per-cylinder engine—built for the 651100—was too big for AMA Superbike and world championship endurance races. Suzukis in those events used an older, 997cc two-valves-per-cylinder engine.

Suzuki engineers were certain that race engines based on the newer four-valve design would make more power, and were eager to get them on the racetrack. On the other hand, more people bought 1100сс street motorcycles than bought 1000cc street motorcycles. The solution was to reduce the bore of the 1074cc four-valve engine and install it in the limited production, 998cc GS1000S Katana.

AMA rules for 1983 limit Superbikes to 750cc, and endurance rules are scheduled to follow the move to less displacement. The rule changes make the distinction between 1074cc and 998cc a moot point, and the 1983 Katana has the bigger engine and the model designation GS100S.

The engine is the same as used in other 1983 four-valve Suzuki 1100s, with more power than 1981 and 1982 versions of the engine.

Bore and stroke are still 72 x 66mm (the GS 10005 Katana's bore was 69.4mm) and the engine still features TSCC (Twin Swirl Combustion Chamber), a design theorized by an Italian and licensed and put into metal by Suzuki. TSCC divides the combustion chamber dome into two oblong sections with a shallow ridge running down the middle front to rear. Each half of the chamber has its own intake and exhaust valves. The shape of the combustion chamber directs incoming fuel and air forward across the combustion chamber, downward along the front of the cylinder, back across the flat-topped piston, and upward along the rear of the cylinder, creating two vertical, rear-to-front swirls which promote complete mixing of gasoline and air and better distribution of that mixture throughout the cylinder.

The cylinder is thus more completely and evenly charged during the intake stroke, improving combustion efficiency and producing more horsepower and better mileage.

The four valves in each combustion chamber are operated by dohc via forked rockers with conventional screw tappets, each rocker and cam lobe opening two valves. The cams run in the cylinder head casting and are driven by a roller chain off the center of the crankshaft. The cam chain tensioner is spring-loaded and advances automatically.

The crankshaft is pressed together and uses roller bearings. Connecting rods are one piece. Primary drive is helical gear direct from crankshaft to clutch basket, and there are two transmission shafts, one carrying the clutch and the other carrying the drive chain sprocket.

The exhaust system is 4-into-2 with a balance tube under the engine. Four Mikuni CV carburetors feed the cylinders. Ignition is electronic, transistor controlled, with a mechanical advance.

Several changes increased horsepower for the 1983 engine. Intake valve timing was advanced 8° by relocating the intake cam sprocket holes, and both intake and exhaust valve lift have been increased 0.5mm. The airbox now has two inlet holes with almost twice the area of the single inlet hole used in 1982, and the airbox has new rubber velocity stacks to suit the increased air intake capacity.

A new air filter flows more air, and carburetor main jets, pilot air correction jets and pilot fuel outlets are all bigger. The exhaust system is less restrictive, featuring changes to the collectors plus larger muffler passageways.

The changes are good for 3.0 horsepower, bringing engine output up to 108 bhp at 8500 rpm.

Beyond the changes made to increase power, other modifications were made to better handle the power the engine al- ready had or to deal with the extra power.

The new pistons are forged, not cast. The alternator rotor pin is 4mm larger, and the taper on which the alternator rides is more gradual, changed from 1:5 to 1:7, to reduce the chance of the alternator spinning off its shaft. The alternator rotor is larger, too, and puts out more power, 280w, 30w more than before. There are more, thinner, clutch plates packed into the same size clutch basket to increase clutch surface area, one extra drive (steel) plate and two extra friction plates. Clutch spring material has been upgraded to better resist heat-induced loss of tension.

The extra power made the 1983 Katana the quickest stock motorcycle Cycle World has tested, with a quarter- mile elapsed time of 11.05 sec. and a terminal speed of 123.64 mph. That's quicker than the 1982 Katana (11.32 sec. at 120.00 mph), the 1983 CB1100F (11.13 sec. at 120.48 mph), the 1982 GS 1100Е (11.10 sec. at 120.32 mph) and the 1982 GPz 1100 (11.18 sec. at 120.16 mph). But judging by terminal speed, a good indicator of horsepower, the Katana should produce a shorter elapsed time at the dragstrip. A CB 1100F, for example, would probably run deep into the 10-sec. bracket if it had enough power to reach a terminal speed of 123.64 mph. But the Katana is held back by the shape and location of the gas tank and seat, which restrict rider position and movement, and by a rear wheel and tire much narrower than the wheel and tire on the CB1100F.

So the rider can't move around as freely on the Katana to correct for wheelies or wheel spin, and the rear tire provides less traction. Both factors make good launches more difficult, and the rear wheel often spins after a power shift from first to second gear.

On the bright side, the new clutch stands up well to dragstrip abuse, completing pass after pass without slipping or grabbing. The extra plates make a huge difference.

The Katana 1100 engine doesn't feel as highly tuned as its output, specifications and performance would indicate. Hot or cold, it fires with half a spin of the starter, and it idles without choke a minute or so after cold start, idles so well that the rider fears it will quit, which it doesn't. At cruise on the highway, at 60 or so there's a trace of surge, not terribly bad and no worse than other Suzukis with less sporting pretension. There's a trace of ping under power below 2500 rpm, a situation easily avoided.

Oddest of all, the 1100 vibrates less than the 1000 Katana did, although we can't say whether it's because the engine balance has been changed by the larger pistons.

While the Katana accelerates hard, it really isn't meant for the dragstrip. The Katana is meant for speed and the appearance of speed, and it is more at home running near redline on a deserted road than it is doing burnouts prior to staging at the drags.

The first Katana, the 1982 model, wasn't much good for anything but straight-line top speed; the unyielding suspension was practically rigid at speeds less than 90 mph and even then couldn't handle small bumps or ripples. Throwing the 1982 model into a fast, bumpy, sweeping turn produced wobbles and sideward hops over pavement irregularities, the forks and shocks unable to move enough to keep the wheels following the ground. The rear tire slid under acceleration out of turns because the suspension didn't react and couldn't keep the tire firmly in contact with anything except billiard-table-smooth tarmac.

That's all changed with the 1983 Katana. This Katana works in sweepers, keeps the wheel on the ground charging out of corners, doesn't beat the rider into pudding on the freeway, doesn't bounce off the ground on concrete highway expansion joints.

The changes started with new progressive spring rates for the front forks, with an initial rate 30 percent softer and a secondary rate 15 percent lower, compared to the 1982 Katana spring rates. Rebound damping was softened by about 50 percent.

Similar changes were made to the rear shocks. The springs are now dual rate, replacing the single-rate 1982 springs. The initial rate of the new springs is about 10 percent lower and the secondary rate is about 20 percent higher. The overall rear shock spring rate is about 10 percent higher, but a 40 percent reduction in compression damping must be considered. Rebound damping across the range of four adjustments has also been reduced an average of 50 percent.

The net effect is that the forks and shocks now respond well to small bumps and will have excellent resistance to bottoming over big bumps at high speed.

The Katana's forks have adjustable spring preload with three positions. The forks don't have air caps or fittings so pressure isn't adjustable. The forks do have anti-dive, using a valve operated by front brake line pressure to re-route fork oil and increase compression damping when the brakes are applied. The system incorporates a blow-off provision—the valve which redirects fork oil is spring-loaded on its seat—so the forks can react to ripples encountered during hard braking.

The shocks have five preload adjustment positions and, as mentioned, four rebound damping adjustment positions.

For a 145-1b. rider, we found that minimum spring preload on both ends and minimum shock rebound damping works best for high-speed riding. At those settings, cornering speeds are determined by available hard-part clearance—the side and centerstand drag on the left, the centerstand and exhaust system drag on the right.

The suspension working best at speed with minimum settings is a testimony to how far off the spring rates and damping rates were on the original Katana.

It's fairly easy to figure out that if the Katana's suspension works best on a racetrack when adjusted to minimum settings, then it will be too stiff for comfortable street use on uneven or choppy roads. It is. The Katana's suspension is stiff. But a rider on a 1983 Katana won't catch himself looking down to see if someone stole his bike's shocks and replaced them with wrought iron struts when he wasn't looking. That could have been the case with the 1982 Katana.

Just as the Katana's suspension is best suited to high-speed work, so is the Katana's seating position. The clip-on handlebars and rearset pegs put the rider into a crouch over the gas tank, a crouch just like the one assumed by riders on Formula One racebikes.

Sitting bolt upright at very high speeds on a motorcycle with normal handlebars turns into a battle to hang on in the face of the wind blast over 90 or 100 mph, which is why Formula One racebikes have the seating position they have. That's also why the Katana's seating position and small windscreen work so well at extra-legal speeds. But around town or at legal highway speeds or when splitting lanes through traffic (in states where that's allowed) there isn't a rush of air on the rider's chest and all his weight is supported by his wrists on those stubby, cast-aluminum bars. It's worst when splitting through traffic, right hand working the throttle and covering the front brake lever at the same time, an ache developing in the web of the hand and spreading to the wrist and up the arm. At least this year's Katana has new grips without Suzuki's traditional blister-raising, sharp ridges.

But if the Katana doesn't make the rider comfortable at slow speeds, it still makes him look fast. Image has a lot to do with the Katana's appeal. It is different enough to catch attention everywhere it goes, attention from motorcyclists and motorists alike. This year a dark blue band covers the top of the fairing and gas tank, offset from the predominant silver paint by two narrow, contrasting blue stripes. The rider's section of the too-hard-after-30-minutes seat is still blue, and the passenger's section gray, but this year the vinyl seat has a smooth, glossy finish instead of the imitation suede finish seen on the original Katana. The vertical rubber fins hanging from the nose of the '82 model's fairing are gone, and the engine and carburetors are painted black, as are the fork sliders. The cast wheels have a new spoke design and are painted black with polished aluminum highlighting the edges of the spokes and the sides of the rim.

There are changes to the instrument panel, a 150-mph speedometer replacing the 85-mph speedometer mandated by a now-rescinded order from the N HTSA. That big-number speedometer is reasonably accurate, reading dead true at 30 mph and reading 60 mph at an actual 58 mph, which is better than other higher-than-85-mph speedometers we've tested.

A new addition is a red light that warns when the sidestand is down. The light mounts on its own bracket ahead of the upper triple clamp and is triggered by a spring-loaded switch positioned near the sidestand frame bracket.

Despite the larger engine and the sidestand warning system, the 1983 Katana weighs 3.0 lb. less than the 1982 Katana. That's because cast aluminum shift and brake pedals and footpeg bases have replaced the steel parts used in 1982.

What hasn't gotten lighter is the Katana's price tag, now up to a suggested list of $4599. It's a high price, fully $900 more than the CB 1 100F, but exclusivity never comes cheaply. What the Katana has is a different look, a taut feel and a love of speed. What the Katana offers is image, a quality which, to the right person, can never cost too much.

Sourc Cycle World 1982