Suzuki GSX1100: Four-valve flyer

Bike Profile

Wayne Waddington's Australian-delivered 1981 Suzuki GSX1100ET (GS1100E).

Story: Jim Scaysbrook • Photos: Sue Scaysbrook

“The fastest standard motorcycle in the world”. That’s not a bad opener in any sales pitch, and it came at a time when motorcycling was all about speed, power and pace.

The all-new 4-valve-per-cylinder GSX1100E hit the market in August 1979; a 100 horsepower, 1074cc missile weighing 243kg. In Australia, ‘race’ meant Castrol Six Hour Race, but there were insufficient quantities of the new Suzuki in the country to meet the homologation requirements prior to the closing date for entries, so the tried and proven GS1000 was used. And to good effect too, as Alan Hales and Neil Chivas won the race, finishing three laps ahead of the second placed Yamaha XS1100.

Officially, the new Suzuki was called the GSX1100ET – T representing Suzuki’s year code for a 1980 model. Although the new 4-valver was also destined for the US market, it was called the GS1100E in the States. The model continued virtually unchanged for 1981, when it became the GSX1100EX, but was substantially restyled as the GSX1100EZ for 1982. This model incorporated styling cues from the Katana, and also dispensed with the original model’s unusual leading-axle forks. Major work inside the engine boosted power to 111hp at 8,500 rpm, while weight dropped to 237kg. With minor tweaks, the 1982 Z model continued until October 1988 in D, E, F and finally G designations. 

A 1983 GSX1100 owned by Melbourne VJMC Member Hans Stegeman, with non-standard exhaust system. Considerably influenced by the Katana styling, with conventional centre axle forks.

The 1984 E model copped the biggest changes yet, with the engine increased in capacity to 1135cc with a power output up to 124hp at 8,500 rpm. This was to remain the specification until the end of the model’s run in 1988.

But back to the beginning. Four-valve technology was all the rage in 1979, when the GSX1100 arrived, along with its smaller sibling, the GSX750. Honda already had four-valve models in the CBX 1000, the CB900 and the CB750, and would soon introduce its racer-for-the road, the CB1100R, while Yamaha and Kawasaki had yet to embrace the technology for their big bikes. The new Suzuki was a quite conventional looking motorcycle, and like its rivals, pitched as a tourer. There was an angular theme to the styling – the square look that carried through to the headlight, the instrument panel, tail section and even the turn indicators. Tourer it may have been, but that didn’t stop Suzuki expounding the performance credentials to the limit. 

The engine was virtually identical to the two valve GS1000, with pressed-up crankshaft running on roller bearings, and chain drive to the dual overhead camshafts.

Mind you, performance could be a dual edged sword, as many markets (notably Germany) were in the process of imposing a 100 horsepower limit, and manufacturers were of two minds as to whether to produce models in different states of tune for various markets. The outgoing GS1000, with its 2-valve head and technology dating back to 1976, put out a claimed 90hp, so it would seem that the new 1100, sporting what Suzuki called TSCC (twin swirl combustion chamber), with twice as many valves and almost 10% greater capacity, would have no problem in easily exceeding 100hp. Yet, it did not, officially producing just a shade under the magic number, albeit with much improved low and mid-range torque and better fuel consumption. The TSCC design itself was a complex piece of work, with a central spark plug and a squarish combustion chamber that incorporated a raised ridge between the pairs of valves.  The idea was to create a swirl in the incoming fuel/air mixture to increase the fuel burn speed through more efficient flame front propagation. Instead of the high domed piston and the hemispherical combustion chamber of the two-valve engine, the pistons now were flat-topped. The other major change was the use of short forked rocker arms to operate the valves instead of the camshaft bearing directly on the valve via shims and buckets. Downstairs, the engine was virtually identical to the two valve GS1000, with pressed-up crankshaft running on roller bearings, and chain drive to the dual overhead camshafts. 

The check panel in the instrument cluster lets you know what’s cooking.

Chassis-wise, the GSX remained conservative, with a twin cradle steel frame not dissimilar to its predecessor, which itself was not unlike Suzuki’s first modern era four-stroke, the GS750. However a beefy looking rectangular section aluminium swinging arm (developed by Yoshimura on the factory-supported Superbikes) graced the rear, with a pair of conventional shock absorbers that had provision for adjusting the rebound damping.  The most obvious departure was at the front end, with motocross-style leading axle Kayaba forks, with air assistance and a balance tube joining the two legs. The wheel sizes, 19 inch front and 17 inch rear, were the standard Japanese set up for the time, and the rear, particularly, was of concern to the Production Racing set. While the fat sidewall offered a cushioning effect that was fine for touring, it had the opposite effect on a race track where the sidewalls flexed and overheated the tread. The brakes too, were a bit old school, with two floating-piston calipers working on slotted discs on the front, and a technically superior dual opposed piston caliper on the rear. 

Left: Adjustment for the front fork damping sits at the bottom of each slider. Right: Unusual for a big road bike, the forks have motocross style leading axle attachment.

Hot to trot

In Australia and New Zealand, Suzuki couldn’t wait to get the new four valve 1100 and 750 onto the track, but first there was the wheel/tyre question to overcome. As they had done with the GS1000 that was victorious in the 1979 Castrol Six Hour, Suzuki exploited a loophole that allowed them to fit wire-spoked wheels which were available for the Canadian model – the rear an 18 inch version for which there were plenty of race-developed tyres. The same argument was used for the bikes that contested the 1980 race seasons on both sides of the Tasman, and the year began in perfect style when Kiwi Dave Hiscock gave the GSX1100 a debut win at the Advertiser Three Hour Race in Adelaide on March 23rd. Rob Phillis on another Suzuki was second. Seven weeks later, Hiscock continued his merry march at the Perth Four Hour Race, this time teamed with Neil Chivas, again with Phillis second. Could the dream run continue? The next major production Race was the Calder Two Hour in August – a race of total carnage when half the field crashed out during the course of the event. And at the end it was that man Hiscock again, leading home team mate Chivas. 

Top left: GS1100 badge denotes the US origins. Above left: Australasian models sported GSX1100 badges. Right: Neil Chivas and John Pace with their 1980 Six Hour GSX1100.

Suzuki could be excused for feeling smug in the lead up to the all-important Six Hour in October, but copped a reality check in the traditional curtain raiser – the Pirelli Three Hour at Surfers Paradise on September 14. Neil Chivas led most of the way, but in the closing minutes was displaced by Hiscock, this time paired with Alan Hales. Crossing the line in third place came Malcolm Campbell/Rod Cox, making it a Suzuki 1-2-3. However post-race scrutineering revealed all three teams had made illegal modifications (welding on the inside) to the alternator covers, which were prone to being ground away on the predominantly right hand corners, and they were disqualified. There was still some joy for Suzuki as Rob Phillis, originally fourth, was instated as the winner. Indeed, the lack of ground clearance on the left side became the Achilles Heel of the GSX1100; the alternator cover doomed to a life of dragging itself along the tarmac until a crack developed and precious lubricant began escaping. 

Dave Hiscock in action on the wire wheeled GSX1100 in the 1980 Castrol Six Hour.

And so to the big one at Amaroo Park. The Unlimited class saw five GSX1100s ranged against eight CB1100R Hondas, but there were also six GSX750 entries in the 750cc class, and in the right hands these were considered a threat due to their better fuel consumption. A trump card for Suzuki came with the arrival of a shipment of 1100s fitted with the lighter spoked wheels, and vitally, wider rear rims – 2.75 x 18 instead of 2.15 x 18 as on the earlier models and on all the Hondas. This allowed the use of the new 130/80V18 Pirelli tyres, which coincidentally turned up around the same time. 

With the Honda CB1100R ruled ineligible for the 1981 Castrol Six Hour, Wayne Gardner turned to the GSX1100.

Despite the posturing and preparations, pre-race form went out the window when race day dawned grey and wet, and pretty much stayed that way. The race developed into a soggy battle between the Honda CB1100R ridden by Wayne Gardner and Andrew Johnson, and the Suzukis of John Pace/Neil Chivas and Alan Hales/Dave Hiscock. As the track dried late in the race, Hales dropped his Suzuki, but Pace kept up the attack and although Gardner took the chequered flag first, Suzuki was adamant that the Pace/Chivas team had in fact completed 323 laps – one more than the winning Honda. The furore continued for eleven months. After three separate hearings, twice dismissed, Suzuki’s appeal was heard on February 7, 1981, and this time upheld; Pace and Chivas were the winners. Or were they? Five months later, a counter appeal by Mentor Motorcycles, entrant of the Gardner/Johnson Honda, was finally heard, and here a separate issue arose – that John Pace had been in the saddle continuously for 3 hours and 56 minutes, when the FIM regulations stipulated that three hours was the maximum for any rider in any one session. The team was docked 52 minutes worth of laps, placing it second last of the 33 finishers on 271 laps. 

Neville Hiscock splashes to victory on the GSX1100 in the 1981 Six Hour.

It was an unsatisfactory outcome for both Suzuki and Honda, who had been prevented from advertising their success while the matters were under review. By the time the 1980 result was confirmed, the 1981 race was only four weeks away. This time, in another wet race, Suzuki did win, but there was no Honda opposition as a new rule required motorcycles to have dual seats and be capable of carrying a pillion passenger, which the CB1100R failed on both counts. As well as taking the first two positions outright, a Suzuki GSX750 won the 750 class. The 750 win was poignant, since it reflected the global trend away from the big bore machines and onto a new breed of lighter, more technically advanced machines. 

Even though this is a 1981 model, it is different to the bikes they used for the Castrol Six Hour Race. They had steel swinging arms, wire spoked wheels, different damping and individual air caps on the forks, whereas this one has a coupling for the air between the fork legs.

A closer look

The red model featured here is an Australian-delivered 1981 machine, belonging to former commercial pilot Wayne Waddington. “I am only the second owner and apart from the paint, which was done about 15 years ago, it is completely original,” says Wayne. “The odometer says 80,000 km, but you can add at least 100,000 to that, and it is probably a few horsepower down on what it should be, but you would expect that after 35 years. Even though this is a 1981 model, it is different to the bikes they used for the Castrol Six Hour Race. They had steel swinging arms, wire spoked wheels, different damping and individual air caps on the forks, whereas this one has a coupling for the air between the fork legs. I have my own theory about why this model has the leading axle forks, whereas the Katana and the later model GSX models had conventional centre-axle forks. The damping mechanism is quite complex and is adjusted by the caps at the bottom of the legs. I think with this set up it was impossible to have the axle in the normal position, so they put it at the front. This may also be why this model has a reputation for being a bit vague in the steering at around 120 km/h. Mind you, if you have faith and just ride through this point, it doesn’t get any worse.”

Speaking of handling, Wayne recalls a chance encounter that shed considerable light on a problem area. “We were having a picnic on the banks of the Parramatta River in 1982 and I got talking to this chap who was on walking sticks and I mentioned that with Pirelli Phantoms fitted, the handling was particularly twitchy.” He replied, “That’s because the Pirellis are 5mm lower in height to the standard Bridgestones. Drop the forks through by 5mm and that will fix it.” “While I was wondering about this comment, I recognised the other chap in their group as Murray Sayle, and then I twigged to whom I was talking – Warren Willing. Needless to say, he was dead right.” 

“Although I haven’t restored or rebuilt this bike, I have overhauled the front forks to try to make them work better and because they had water in them from being stored”, says Wayne. “I replaced 28 items in the forks – o-rings, seals; there are five o-rings alone in the air coupling that connects the fork legs.”

Garry Hocking’s 1982 US model Suzuki GS1100.

Our blue machine is a US model of 1982 vintage owned by Garry Hocking (the Sydney-based guru of the quirky Yamaha TX 750), hence the GS1100 badges in place of the local GSX1100 badging. Although the engine specifications are identical with the 100 hp versions sold elsewhere in the world, there are a number of other subtle differences. The front forks are much plusher in operation due to larger bleed holes in the damping units, and the forks springs are also less stiff than the European and Australian versions. Visually, the most obvious difference between the US and the Australian version is the fuel tank – a 19 litre job on the US bike whereas the vast majority of the others have 24 litre tanks.

The GSX1100 in its element; going fast.

I rode both bikes, albeit briefly, and to me there wasn’t a lot of difference; they both felt quick enough without being brutal, handled very well, and Wayne’s bike especially had excellent brakes. Invariably, the GSX 1100 is compared to its arch race track rival, the Honda CB1100R, but they really are poles apart. To the Suzuki’s credit, it was more than a match for the Honda, which was an out-and-out racer for the road. By comparison, the Suzuki is a rapid road bike that also worked extremely well on the track. You could ride all day in comfort on the GSX, whereas you’d be eagerly awaiting the next fuel stop on the CB1100R. 

 Specifications: Suzuki GSX1100ET (GS1100E) 1980

Engine: Four cylinder DOHC 4 valves per cylinder. Air cooled.
Bore x stroke: 72mm x 66mm
Compression ratio: 9.5:1
Lubrication: wet sump
Induction: 4 x 34mm Mikuni BSS4SS
Ignition: CDI
Power: 100hp (72.9kW) at 8,700 rpm
Torque: 85.3 Nm (62.9 ft lb) at 
Transmission: 5 speed
Final drive: 630 chain
Front suspension: Kayaba telescopic forks 37mm, 130mm travel
Rear suspension: Kayaba dual shock absorbers with adjustable spring pre load. 107mm travel.
Brakes: Front: 2 x 275mm discs • Rear: 1 x 275mm disc
Tyres: Front: 3.50 V19 • Rear: 4.50 V17
Rake/trail: 28º/103mm
Wheelbase: 1549mm
Seat height: 806mm
Weight (wet): 254kg
Top speed: 227 km/h (141 mph)

This article first appeared in Old Bike Australasia Issue 60.