The Yamaha XS1100

Fashionably late for the Superbike ball

| January/February 2010

yamaha xs1100 8

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

Yamaha XS1100
Years produced:
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).

12/22/2015 10:37:31 PM

Heavy. Not a canyon carver, but great, if you have lots of pavement. I have a silver full bagger 1980 (built June '79) and a black/gold '79 Special. Building brakes on the Special; the '80 starts by just thinking about touching the starter button; braided hoses are on the way. I call it "Kong."

3/26/2015 5:38:59 PM

Gorgeous example there Doug. Best colour as you say, and a real torque monster. I remember the bike well, as a pal over here in Ireland owned the very first one brought into my country !! It was a silver example. Some great detail there too in the piece, very good stuff. believe it or not, I still own the original test on this bike from Motorcyclist magazine, article written by Ken Vreeke I think his name was, and they rode the bike from LA to NY in about 36 hrs if memory recalls. great stuff. If memory serves right, it quartered in 11.83 secs at 115.38 mph. Going purely on memory here from 1978 !!! I must dig out the mag from my extensive files !!!! Damn impressive stuff from a 600 lbs plus fully fuelled bike. I currently own a natural successor to that bike, a 1986 Yamaha FJ1200 , and its a powerhouse indeed. I brought that bike back from Boston where I lived up until 2011. Best regards Dave

3/24/2015 12:03:28 PM

I have a "barn find" bike I bought last year. It was originally sold in Anaheim California in the fall of 1978. It was only used 318 miles and had been stored ever since until it was purchased last year. The last sticker on the license plate is from 1981, and I have the registration documents for those 3 years (1978-1981) Luckily the bike was stored in an environment that didn't damage anything. All the mechanical components were like new. The original tires still appeared to be in good shape although they were hard to the touch. Unfortunately they do not make "standard dimension" tires any longer so I replaced them with modern tires of the original brand name but did keep the old ones too. The carburetors were professionally cleaned and reconditioned, the oil in the engine and drive train was replaced and now the bike starts and runs like a brand new motorcycle. Below is a link to some pictures I just took over the weekend. Since I bought the motorcycle I rode it approximately 80 miles, which were mostly test drives at various stages of the "awakening" of the mighty XS11. Here is the link:

12/12/2014 2:43:28 PM

The photo is NOT a photo of the 79 xs100 special! Its the touring model. The special has more of a tear drop style gas tank.

2/15/2014 11:09:53 AM

The ’78 XS1100E Yamaha had styling that at the time (1978) was popular in Europe. Little did we know at the time the Special with completely America styling was due for release the following year. The nearest Japanese competitor bike Honda had was the XS11 in competition with was the ’78 GoldWing 1000. If you did your own maintaince on an unmodified ’78 ‘Wing, you would need, besides plugs, filters and such was two sets of points and two condensers. Now you could do a professional tune-up with a dwell meter rather than feeler gages but you would need two dwell meters to fiddle with two sets of points and two movable timing plates with the engine running. Adjusting the dwell on one set of points would affect the dwell on the other set as well. Adjusting one and then the other set until you hit that sweet spot. Don’t forget setting the timing. The ‘Wing timing marks were on the flywheel accessed by removing a threaded plug over the transition. If you were going to do a professional tune using a timing light, you needed to replace that threaded plug with a plastic clear plug so you could see the timing marks with the engine running and keeping the oil from sloshing out the open timing port. Now with the engine running, plastic plug in place, timing light flashing, you are now ready to set the timing by moving the timing plate with the points you so carefully set the dwell on. Move the plate to adjust the timing and if you still have the dwell meter hooked up, you will notice the dwell change. Readjust the dwell and the timing changes. So you go back and forth until you hit that sweet spot. That is one set of points down and another set to go. You do it all again just to realize that what ever you do to one set of points affects the other set as well. So back and forth until you hit that double sweet spot. Of course all this is mute due to the fact that the oil you did not want to slosh out while doing your timing is sloshing on the plastic clear timing plug making it impossible to see the timing marks in the first place. This is why even Honda mechanics did less than perfect static timing on ’78 GoldWings with feeler gages and a 12 volt light. Now to ignition timing on an XS11 was - - - well the XS11 had pointless CDI timing that eliminated all that. If you did your own malignance, the ’78 XS11 Yamaha was looking darn good.

Scott Lawrence
6/4/2013 1:24:37 PM

The Yamaha's still didn't have the looks of a Honda. The XS1100 may have been fast, but it was boxy looking compared to the Honda's of the same era.

Fred Haska
1/16/2013 4:36:55 AM

I own a 1981 XS 1100. I bought it in March of 2012. Paid $ 500.00 for it. The bike did not run at the time I bought it. Now it runs great. I put new carbs , new battery , new handlebars, reupholstered the seat. Painted the bike. New plugs, all new fluid. New air filter, New gaskets. A new complete charging system, Stator, Field Coil, and new Voltage regulator. New Shocks new tires. This bike is so fast. The only thing that I find very different about this bike is the inaccuracy about the MPG. I check my mileage all the time and I get 48 mpg on every trip. I love this bike, I've been offered 3500.00 for it and I said no way.

7/21/2011 11:25:29 AM

Had a '79 XS11 Special ["XSEleven SF"] back in the '90s. XS11s have their own website [], an offshoot of the email listserve of XSives I once belonged to. Known issues w/ XS11s: the centerstand wasn't designed quite right, so the bike is both hard to get up on the stand and tends to rip the stand off the frame over time: this is in fact, one of the most common points of mechanical failure, right up there w/ munching 2nd gear [ALWAYS use the clutch for gears 1,2&3!] and a leaky seal on the kickstart pivot. BTW, the XS11 wasn't a development of the XS750: Yamaha started somewhat fresh, & then came out w/ the XS850 as a derivative of the Eleven to replace the dead-end XS750. [XS850 pistons are NLA, but you can still get sets for the Eleven & they'll fit the 850 w/ one left over...] For 1980, Yamaha adopted some Hitachi carbs to meet smog requirements: these are non-adjustable, so if you go with an aftermarket pipe [almost a necessity, as a complete NOS exhaust for the XS11 is more $$ than a running bike!], you'll also need to source some of the Mikunis from the 1st 2 model years. Greatest failing of the XS11 is its hunger for fuel: best mileage averages only 35mpg, and it requires carb-balancing at least 1x/mo.; keep tabs on your avg. mileage per fillup, since that's the easiest way to know when it wants another carb adjustment. ;) The handling issues are a known factor, mostly due to wimpy forks on a heavy bike: you can still get a Superbrace for the XS11 to help.

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