Retrospective: Yamaha XT600: 1984-1989

1986 Yamaha XT600
Year/Model: 1986 Yamaha XT600; Owner: Kevin Delaney, Arroyo Grande, California.

As an inveterate reader of motorcycle travel articles and books, in the 1980s and ’90s I noticed that many of our European friends, when headed off to Africa—the equivalent of our southwest—opted to take Yamaha’s big 600cc single-cylinder enduro bike, known as the XT.

If you really wanted to go someplace rough, like the backroads of many African nations, you needed a bike that was stone reliable. And preferably reasonably light in weight in case it had to be dragged out of a muddy swamp, or put in a canoe should the need arise.

1986 Yamaha XT600
1986 Yamaha XT600

In North America we have a pretty well organized system of getting help, everything from the AAA to having a helicopter retrieve a bike that has fallen into a canyon somewhere in the Colorado Rockies. But Africa…that’s different; you want a bike that won’t break down. At some point in the future you will be able to bounce a phone call off some satellite and have a drone deliver a replacement part within 12 hours, but that is still a bit off in the future.

The first Yamaha XT, the 500 version, appeared in 1974 and was well received. That was a two-valve overhead cam motor with a bore of 87mm, stroke of 84mm. After drastically modified versions won the Paris-Dakar race in 1979 and 1980, it caught on big-time in Europe. Those victories were a real good
selling point.

Yamaha decided to up the capacity ante for 1982 and the motor was bored out to 92mm, for a total of 550cc, and the cylinder head got four valves. Yamaha USA was again selling the 550 in 1983, but also available was the TT600, a lightless race bike bored out yet again, to 95mm, or 595cc. For ’84 the factory detuned the TT a little, put lights on, and the XT600 went on the U.S. market.

The oversquare engine was rated at an optimistic 45 crankshaft horsepower at 6,500 rpm, and regardless of how many turned the rear wheel, it was a butt-kicker. No electric leg, just the old-fashioned kickstarter. Carburetion was via dual-stage Teikei carbs, with a primary using a slide-type opening, and then at about half throttle the second constant-velocity carb cut in. Yamaha proudly labeled this its Dual Induction System—or YDIS. Torque peaked at over 30 lb-ft at 5,500 rpm.

1986 Yamaha XT600
1986 Yamaha XT600

The innards were definitely overdesigned and over-engineered, with well-lubricated large roller and ball bearings keeping everything spinning smoothly. It was a dry sump engine, with the oil reservoir located back a ways behind the left side panel. The inevitable vibration problems were considerably reduced by the use of a gear-driven counterbalancer. All this with a reliably modest 8.5:1 compression ratio, sparked by a single plug set in the middle of the four valves—very efficient for combustion, but difficult to access. It was fired by a CDI black box.

Exhaust was via two header pipes, and a single well-protected muffler. Yamaha had learned that its dual-purpose motorcycles would inevitably fall over, and protected the enduro models quite well.

The steel frame used a single downtube to the front of the engine, and a large backbone that came down to the transmission. A big skid plate protected the sump. The front suspension looked like it had taken its styling cues from the competitive YZ models, using a 41mm Showa fork with aluminum sliders, but without any adjustments. Although it did have almost 10 inches of travel. The swingarm was extruded aluminum, and Yamaha’s Monocross single shock with progressive linkage and more than nine inches of travel kept everything comfortably suspended. Comfortable, yes, because Yamaha figured that these bikes would more often be bought by rather soft-core trail riders, rather than hardcore boonie-bashers, and wanted to keep the urbane riders happy. Serious riders could up their own
spring rates.

Wheels were a tall 21-incher in front, 17 at the rear, with mildly knobby tires. Rear brake was a drum, the front a disc that was usable in the soft stuff. On the asphalt, however, it required a major handful. A few of the very early XT600s came in with a front drum, but that was quickly dispensed with. Dry weight was a modest 300 pounds, with the gas tank holding an equally modest 2.3 gallons, good for a hundred miles at best. The aftermarket was quick to fix that, too.

1986 Yamaha XT600
1986 Yamaha XT600

Getting on was a bit of a chore as the seat was more than 34 inches above the ground—what one expects with 10 inches of suspension travel—but riders soon learned to use the left footpeg as a stirrup. Kickstarting was not difficult, since a cable lifted one of the exhaust valves as the kickstarter was engaged. Even when cold, one or two kicks would suffice. Up on the dash the speedo went to 110 mph, and the bike could push the 100 mark. The rev-meter redlined at 7,000.
Snick it into gear, let out the clutch, and away you went. Mild knobbies were adequate on the street, worked OK in the dirt. Many riders felt this was a better dirt road than pavement machine, as it had kept the heart, if not the soul, of the original TT machine.

Then in 1990 the new XT600E came along…but that is another story.

(This Retrospective article was published in the November 2014 issue of Rider magazine.)

1986 Yamaha XT600
1986 Yamaha XT600

1986 Yamaha XT600
1986 Yamaha XT600

2 COMMENTS

  1. hi sr I am looking for parts for a Yamaha xt 600 year 1984 is it possible to give a address of a Yamaha dealer??

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