Three Equals Four: 1979 Yamaha XS750F

Parked in a New York barn for more than 30 years, this 1979 Yamaha XS750F has been carefully restored by its new owner.


| July/August 2016


1979 Yamaha XS750F
Engine:
747.3cc air-cooled DOHC inline triple, 68mm x 68.6mm bore and stroke, 9.5:1 compression ratio, 48.6hp @ 7,500rpm (period dyno test)
Top speed:
112mph (est.)
Carburetion:
Three 34mm Mikuni CV
Transmission:
5-speed, shaft final drive
Weight (wet):
553lb (251kg)
Fuel capacity/MPG:
4.5gal (17ltr)/40-50mpg
Price then/now:
$2,698/$1,500-$4,000

In the mid-1970s, Yamaha’s fiasco with its 1973-1974 TX750 overhead cam twin had sent the company scrambling back to the drawing board to come up with something fresh. Next door neighbor and competitor Honda was selling every CB750 Four it could produce, and Yamaha desperately needed a hit in the 750cc category.

Eager to clean the egg on the face left by the TX, a nice-looking machine with an unfortunate propensity for blowing up crankshafts, Yamaha had to come up with something good to quash the rumors that it didn’t possess the know-how to build good 4-stroke engines. “They should stick to 2-strokes,” was the often-heard comment in bike circles, even though the double overhead cam, 4-valve-per-cylinder TX/XS500 received favorable reviews by the motorcycle press, and Yamaha’s faux Bonneville, the overhead cam XS650 twin introduced in 1970, continued to prove its robust design. But that wasn’t enough: Yamaha wanted a new 750, and it had to make a statement loud enough to silence the critics.

Enter the XS750



Released in Japan in early 1976 as the GX750, the new 750 packed a long list of new features, including a shaft-drive transverse engine, headlights that automatically turned on when the engine started and self-cancelling turn signals. Mechanically, the new bike was unlike any Yamaha before it, sporting a 3-cylinder, 64 horsepower, double overhead camshaft engine, a 5-speed transmission and shaft final drive.

In an attempt to minimize engine girth, the cam chain was placed at the end of the crankshaft, allowing the cylinders to cozy up and decreasing overall top end width. However, because the brushless alternator and the ignition points/starter clutch were placed at each end of the crank, the engine was a bit chunky at the waistline, measuring 20.5 inches from cover to cover, the same as Honda’s 750 four. Primary drive was via a Hy-Vo chain wrapped around an inward- instead of outward-facing clutch hub. A stout 4-point mounting bracket held the clutch in place and a rubber disk imbedded in the clutch cover helped dampen vibration and clutch noise.

TimKern
6/23/2016 10:08:02 AM

Had an -E model several years in the early "aughts." Smooth, plenty fast, nice handling, reliable as a stone axe. Good-looking yet unpretentious, it was a quiet, good friend.


JOHNB
6/23/2016 8:17:50 AM

Hello John. That's an incredible find you landed. To finish breaking in the engine/trans for a 1979 XS750F is a rare event. But I suggest that you not save it for the next owner to ride. Ignore the odometer and ride it to enjoy it. I owned a 1978 XS750E in red and gold trim for 26 years and with 36 k miles I passed it on. Except for that skipping 2nd gear issue, the rest of the bike ran great and was noticed and appreciated sometimes even by Harley riders. And those stock pipes made a really good sound. You did a super job bringing your '79 F back to perfect condition, and I envy you your ride! Thanks to all for the pro pictures and great story. JohnB in n.IL.


ArthurMCC
6/20/2016 1:30:24 PM

Hi, John. The latest issue of Motorcycle Classics was shipped to subscribers on June 14, and will be on newsstands on June 21!








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