The Yamaha XS1100

Fashionably late for the Superbike ball

| January/February 2010

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    The first year for the Yamaha XS1100 is really the most striking because of the maroon paint, gold pinstriping and the gold emblems on the side covers.
    Photo by Doug Mitchel
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    The Yamaha XS1100.
    Photo by Doug Mitchel
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    The Yamaha XS1100.
    Photo by Doug Mitchel
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    At 1,011 cc the Yamaha XS1100 was the biggest Japanese four yet.
    Photo by Doug Mitchel
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    The broad, flat seat on the Yamaha XS1100 is a good place to spend a day.
    Photo by Doug Mitchel
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    Shaft drive pointed to the touring aspirations of the Yamaha XS1100.
    Photo by Doug Mitchel
  • yamaha xs1100 7
    The Yamaha XS1100.
    Photo by Doug Mitchel
  • yamaha xs1100 6
    The Yamaha XS1100.
    Photo by Doug Mitchel

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Yamaha XS1100
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)
MPG: 30-40
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).

Larry.C
3/26/2019 7:04:40 AM

I just picked up a 1981 xs 1100 trans Canada barn find . Its in rough shape but I hope to bring it back to its original glory. Does anyone know of decent threads or parts suppliers either in Canad or the Us . I can be reached at larrysunnyridge@gmail.com


marc
3/8/2019 10:13:14 AM

I owned a 78 about 20 years ago, and it was, as article mentions easy to ride for a big bike. Mine had a Kerker 4into1 and it sounded nice, performance was good (I raced a Maico 490 at the time) so it didn't feel as fast as it actually was, as Maico would pull your arms off! Sure was a mile eater, I favored a BMW 1100, only for the fairing & windshield, as that was the first windscreen (crotch rocket fairing/windscreens don't really count) bike I ever had. In retrospect, shoulda put one on yamaha, as it had more power & was smoother overall!


Robert
1/4/2019 12:12:27 PM

Enjoy riding my 1978 XS 1100 E And 1979 XS 1100 SF. Great riding bikes they where over engineered and will out last most bikes still after 41 years. If looking for fast my 1979 XS 1100 SF with a Mr. Turbo Kit does great 168 hp on rear wheel.




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