The Yamaha XS1100
By Doug Mitchel
Years produced: 1978-1981
Claimed power: 95hp @ 8,000rpm
Top speed: 136mph (period test)
Engine type: 1,101cc air-cooled, DOHC inline four
Weight: (wet) 602lb (274kg)
Price then: $2,989 (1978)
Price now: $1,500-$4,000
When the time came for Yamaha to join the Superbike ball, the Yamaha XS1100 (also known as the Yamaha XS Eleven) was fashionably late. Liter bikes from Honda, Kawasaki and Suzuki were already at the dance and making a name for themselves. Although the competing entries filled different needs, each was powered by an engine displacing 1,000cc or more.
Honda had broken the 1,000cc barrier with the Honda GL1000 in 1975. It was followed by the Kawasaki KZ1000 in 1977, and then the Suzuki GS1000 in 1978. Until 1977, Yamaha’s biggest model was the Yamaha XS650 twin. The triple-lung Yamaha XS750 rolled into view for 1976, but left much to be desired when it came to a highway touring motorcycle and was a bit of a slug when you rolled on the throttle.
Not just bigger, better
Knowing they needed a bigger partner to compete in the hoedown, Yamaha turned up the wick and introduced its XS1100 for 1978. Much of the media had expected a 1,000cc machine to fill the spot, but the designers at Yamaha threw an unexpected performer onto the dance floor. Not only did the latest XS carry more cubic centimeters than the others, but it also featured a 4-cylinder engine, a first for the tuning-fork firm. With Yamaha’s sights set on the long haul rider, the big XS was armed for bear.
On the surface, the XS1100 seemed pretty straight forward, but like a lady behind a feathered mask it hid a few surprises. When the engineers were drawing up the 1,101.6cc engine, they did far more than simply tack an extra lung to the existing 3-cylinder engine from the XS750. While being fairly typical in its layout, Yamaha threw in some technological features to enhance power. Dual overhead cams were expected, but the four 34mm Mikuni constant velocity carbs — a first for an inline four — weren’t. The XS also benefited from very unique combustion chambers.
While hemispherical combustion chambers, with intake and exhaust valves placed across from each other and a centrally located sparkplug (hence the term “hemi head”), were the performance norm, they had inherent limitations. Chief among them was upping compression ratio without resorting to pistons with huge crowns, increasing weight and slowing heat dissipation. To get around this, Yamaha developed a complex “polyspheric” combustion chamber, a design that required six machining operations to achieve. The multitude of cuts and shapes milled into each combustion chamber produced the same volumetric efficiency of a hemi but without any of a hemi’s drawbacks, allowing Yamaha to use slightly crowned and lighter weight pistons (211 grams).
A second feather in the designer’s cap was the ignition system. Borrowing from the automotive world, the new XS included transistorized ignition with vacuum advance, the former for reliable firing, and the latter to greatly improve mid-throttle and trailing throttle performance thanks to its ability to advance ignition timing when it’s most needed. This helped the big engine to deliver power smoothly regardless of rpm or selected gear.
Final drive on the bike was shaft, chosen primarily for the goal of making the XS Eleven a highway touring motorcycle. Five gears sent their ratios to the shaft without any ruckus, and without undue rear-end lift under hard acceleration. It was there, just not as pronounced as what riders of BMWs were accustomed to. Disc brakes in triplicate, two fore and one aft, did a great job of hauling the heavy XS down from your chosen velocity. Each rotor measured 11.7 inches in diameter and was squeezed by a single-piston caliper.
Not just bigger, faster
Obviously, Yamaha didn’t go to all this effort to end up with lackluster performance. Curb weight for the XS1100 was listed as 602 pounds with a full tank of fuel. With a rider aboard, that number could easily reach 800. Add a passenger and the half-ton was within reach. Pushing that much mass through the atmosphere seemed to be a herculean task, but the XS1100 proved its worth.
When Cycle magazine took an XS1100 to the local drag strip for its January 1978 issue, the massive XS laid down speeds never before seen by a Superbike of the period. Nineteen runs were made, with every trip of the lights coming in under 12 seconds. Their best run was 11.82, a time unmatched by any bike prior to the XS. A month later, Cycle World reported a best run of 11.78 seconds. The motorcycle world had a new king of the quarter mile.
The styling of the big XS1100 standard was fairly staid, belying the power that lurked within. Hints of European design could be found in the 5.3-gallon fuel tank and rear seat cowl, both trimmed with gold pinstripes. Unlike most offerings of the day, the saddle did not hinge up for access. The cowl and seat was a singular item and needed to be unbolted to service the battery. A standard issue tool kit lived under a lockable side cover but displaced all the storage to be had. The seat itself was wide, well padded and made a great place to spend the day. Even the passenger portion of the seat was comfortable, allowing a friend to go along as you took to the long ribbons of tarmac.
The handlebars were another creature comfort that held a secret. At first glance they appeared to be too far back and at too extreme an angle to be user friendly. Once perched on the bike, riders found they were about as perfect as they could be, affording a comfortable, day-long ride posture. Another part of this ergonomic victory was due to the position of the foot pegs, which were slightly rear set.
A “custom,” called the XS Special, was offered alongside the standard, and included features like a tear-drop fuel tank, 2-step saddle and taller, buckhorn bars. The custom configuration was all the rage in the day and the XS Special slotted in nicely. A Midnight Special drenched in black with gold trim came later.
Brand new, the XS1100 carried an MSRP of $2,989, making it cheaper than its liter-bike-plus rivals. The Honda CBX commanded nearly $1,000 more, while the Kawasaki Z1-R and Suzuki GS1000E were almost $800 more.
The downside to bigger
It would seem the new Yamaha XS1100 was the perfect bike for any occasion. Indeed, when devouring miles that came in a straight line, the XS was at the top of the food chain. The smoothness of the engine coupled to comfortable accommodations made for a machine that could eat highway miles without a hint of indigestion. It was only when the bike was pressed into cornering at high speeds that things turned ugly. Testers of the day all echoed the same story: The XS1100 was a solid bullet in a straight line, but cornering at high speeds was done at your own risk.
Cycle warned its readers that the bike could easily go, stop and steer — just never two at the same time. A high-speed wobble came on readily if you pushed the 600-pound machine too hard into the turns. And while the point at which this happened was above most riders’ skill set, that didn’t make the issue any easier to deal with. Excessive exuberance would quickly expose the bike’s weakness and send you offroading on a machine not intended to do so.
I had a brief opportunity to ride Joe Bortz’s XS1100, our feature bike. Being vertically challenged (OK, I’m short), the 32-inch saddle lifts my boots higher off the pavement than I like while at rest. But once under way that issue disappeared as I transitioned to the experience of mind-numbing acceleration and a mount I could ride all day. Turning the beast around is effortless and smooth, as if I’d been riding it for years. The 61-inch wheelbase would seem to suggest a different experience, but the XS Eleven surprised. I remember riding a Midnight Special version of this bike when they were new. A buddy had purchased the bike and was eager to let me take a spin. Even in the height of my youth, I was amazed at the speed and balance of the Yamaha. My personal mount at the time was a Honda CB750 with the early single-cam engine. It had been impressive until the day I threw my leg over the XS1100. How quickly legends fall …
Owner Joe loves the Yamaha. “I find it very appealing,” he says. “The first year for the XS1100 is really the most striking because of the maroon paint, gold pinstriping and the gold emblems on the side covers. This is an extremely comfortable bike, and when I compare it to the other large bikes of the period, such as the 1979 Honda CBX 6-cylinder and the 1979 Kawasaki KZ1300 6-cylinder, its riding position, seat, and distance between the seat and the handle bars is the most comfortable of the three. As far as spending many hours in the saddle on a road trip, I’d prefer the XS1100 over the Kawasaki or the Honda.
“Motorcycles appeal to all the human senses,” Joe continues, “and one of those is sound. Of the three bikes — XS1100, CBX and KZ1300 — the XS1100 definitely has the best low-end growl. It’s not quite as good as an MV Agusta America or a Laverda Jota, but it’s darn close.”
The XS1100 was replaced by the Maxim in 1982, as Yamaha did its best to keep up with the manic changes within the industry. Those were the golden days of cycling, with classic machines coming out every year. Had I seen the writing on the wall, I would have saved a few that I owned, but my common sense gene had yet to make its appearance. Youth, as the saying goes, is wasted on the young. MC
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