1973 Yamaha TX650
Claimed power: 53hp @ 7,000rpm
Top speed: 105mph (period test)
Engine: 653cc OHC air-cooled vertical twin, 75mm x 74mm bore and stroke, 8.7:1 compression ratio
Weight (dry): 420lb (191kg)
MPG: 3.3gal (12.5ltr)/47mpg (observed)
Price then/now: $1,399/$3,000-$5,500
1970 heralded a new age of multis. Honda had its revolutionary CB750 Four, Kawasaki its fearsome Mach I triple — even the staid Brits had the Triumph/BSA triple. So what did Yamaha do? Why, introduce a thoroughly traditional 650 parallel twin of course — but with a twist.
Badged the XS-1 when it first went on sale as a 1970 model, Yamaha’s new 650 twin was an interesting mix of an old-school favorite — 360-degree, 650cc parallel twin — wrapped in new-school technology. Although it looked — by design — much like its British inspiration (specifically, Triumph’s 650 Bonneville), Yamaha’s new twin was not like twins of yore. Intelligent application of new technology meant it breathed easily (thank you CV carbs and overhead cam) and spun happily, a light flywheel accentuating the engine’s instant throttle response. It also didn’t leak oil, thanks to modern tooling unit engine/transmission construction with a horizontally-split crankcase, superior to vertically-split cases for controlling crankcase flex and subsequent loosening of critical sealing surfaces.
A model with legs
Yamaha’s new-meets-old approach paid dividends, and the 650 twin rapidly gained favor with U.S. buyers. Although it wasn’t really any more powerful than a contemporary Triumph Bonneville 650 (Yamaha advertised 53 horsepower versus Triumph’s claimed 52) buyers considered it a more modern, easier-riding machine. Brakes were simple drums front and rear, and it was a reliable first-kick runner (electric start and a front disc brake came with the XS-2 in 1972), which was appreciated by regular Joes and Janes who still liked a no-frills approach to motorcycling in an era of increasing complexity. While it generally required little mechanical attention, it was a bike owners could — and still can — easily work on.
It wasn’t always smooth sailing, however. Early bikes suffered a multitude of electrical problems, including blown headlamps, failing batteries and faulty charging systems. Perhaps Yamaha copied the competition too well, as most of those problems were a direct result of to the new Yamaha’s one glaring fault: vibration.
A certain amount of vibration is to be expected from any big twin, but Yamaha received more than a little bad press on the issue. “The footpegs and handgrips fairly tingle,” Cycle wrote in a period review, adding: “Vibration shakes the tachometer, blurring the increment marks between the numbers.” It was an issue raised in just about every review of the bike, with testers finding it tiring to ride for any length of time on the super slab.
It also received some bad press for erratic high-speed handling, but when it came to slower around-town or country two-lane riding, the twin was generally praised as a solid, confident machine. It was no canyon carver, and it was never meant to be, a fact amply evident during the time I spent with our subject bike, associate editor Landon Hall’s 1973 TX650.
Out on the road
Regular readers will recognize Hall’s bike from previous MC How-Tos. Showing fewer than 10,000 miles when Hall bought it a few years back, it perfectly illustrates how easy these bikes are to own and keep on the road. Although equipped with 4-inch-over fork tubes when found (Easy Rider, here I come!), Hall’s slowly brought it back to stock with a new set of correct fork tubes, new fork seals and fluid, a new seat cover, a comprehensive tune-up and an overhaul of the front brake hydraulics. Relatively cheap to buy, it’s been inexpensive to rehab and to ride, making it an ideal classic for everyday use.
To test the 650’s mettle as a real-world classic, I used it for my daily 60-mile commute from home to the palatial offices here at Motorcycle Classics Towers, amassing some 600 miles in the process. Over a two-week period, it reliably delivered me to work every day, never missing a beat, using no oil and averaging 47mpg.
The first time I rode an XS650 was around 1979, when I was looking for my first “big” motorcycle and I tested a used 1975 model. Equipped with a Vetter fairing, it was the biggest bike I’d ever ridden, and its power and torque amazed me. Fast-forward 30-some years and many bikes later, and Yamaha’s “big” 650 no longer feels, well, big. Fact is, it feels almost downright small, which is not a bad thing.
That sense of smallness is accentuated in around-town riding, where the 650 excels. Compared to contemporary multis like the CB750, the Yamaha feels like a bicycle; light, agile and very flickable. The light-action throttle and quick-revving nature of the twin make it feel faster than it really is, and around town it’s a lot like a Bonnie, its narrow beam encouraging you to scoot up close to the tank so you can dive into slow-speed corners with gusto.
Out on the road, things change: Those period testers weren’t exaggerating — this bike vibrates. At lower engine speeds the vibes feel good, giving the engine a torquey, lusty feel. But as revs climb, so do the vibes, and at 75mph the engine’s spinning at 4,500rpm, right where the vibes are the worst. And, ironically, right where the engine seems to be pulling its best. This makes highway riding a chore, because while the 650 will hold 75mph with ease, the vibration, allied with slightly twitchy high-speed handling, will encourage you to stay off the main highway. It’s OK for a few miles, but after 30 miles, it just gets old.
Hauling things down to a stop is a front disc/rear drum setup that’s a bit of a mixed bag. While the front disc bites OK, it has zero feel. The rear drum has slightly better feel, but it’s also a little prone to premature lockup.
The front suspension on this bike was very stiff, even with the recent fork overhaul. While thinner fork oil might help, it’s really no worse than most bikes of the era. Rear shocks are original, and while they have reasonable springing, they have almost no damping. Still, they keep the rear tire reasonably well planted to the road. Modern tires help, but this particular bike would really benefit from some suspension upgrading. Even period testers were critical of the 650’s suspension.
When it’s all said and done
The centerpiece of the big Yamaha remains its engine. Like the Triumph twin that inspired it, it benefits from that classic vertical twin feel, slightly lumpy at idle but beating out the power with authority as the revs climb. Yet compared to a Triumph, the Yamaha engine feels lighter and easier to spin — even if it doesn’t feel quite as broadly powerful as a Bonneville 650.
The clutch is smooth and light (although the cable on our test bike was a little sticky), and the 5-speed transmission shifts beautifully, with no false neutrals, ever. Unlike the last Triumph TR6 I rode, which required a finessed blip of the throttle to get the clutch plates to free up, finding neutral on the Yamaha was easy, and the shift into first was nice and smooth every time; just a little “snick” and it’s in gear.
This is not, we should point out, a bike you can disappear on. Most people think it’s a Triumph until they see the Yamaha badge, and it seems like everyone of a certain age either had one, almost bought one or knew someone who did. A truck driver who stopped me in a parking lot said he traded his ‘73 “back in the day” for a bag of marijuana! “I never should have sold that bike,” he lamented.
Over a 16-year production life, Yamaha cranked out a half-million-plus 650 twins, making it one of Yamaha’s most successful models ever. U.S. sales stopped in 1983, but they were available in other markets into 1985, when production finally came to an end.
Classically proportioned and endowed with solid mechanicals that deliver years of reliable service, Yamaha’s big twin has rightly become a favorite of classic bike fans everywhere. A natural base for the street tracker or café treatment, they’ve inspired a huge aftermarket, making parts and support easy to find. MC
Read Randy's Cycle Service: Yamaha TX650 Advice and get an expert's opinon on how to maintain your classic Japanese Motorcycle.