Yamaha FJ 600

As a look-alike little brother to the FJ1100, the FJ600 promises true sporting performance. Though a few engine parts were borrowed from previous machines, the FJ600 is essentially all new and aimed squarely at sports riders. The 16-valve engine features valve sizes normally reserved for 750s: 31.5mm intake, 27mm exhaust and the four carbs boast large 32mm Venturis. Power is transmitted to the chain-driven rear wheel through a six-speed gear box. A frame-mounted fairing, triple discs, DeCarbon-type single-shock rear suspension system and long-travel front suspension with integrated fork brace adorn the short (56.1-inch wheelbase), low-slung chassis.

1984 Review

Yamaha's middleweight will get its sport reputation the hard way— by earning it.
With all of the attention that's going to be paid to Yamaha's other new sport-bikes, the FJ600 just might get pushed out of the limelight. After all, this straightforward transverse-four middleweight isn't, as is the RZ350, the triumphant return of two-strokes to U.S. streets; nor is it, as Yamaha proclaims of its new FJ1100, destined to be 1984's fastest production bike.
And perhaps, in specification, the 600 is unspectacular by 1984 standards. Its all-new chassis includes Monoshock rear suspension (with preload set via a remote adjuster), but neither the deCarbon shock nor the air-assist fork allows damping adjustment. On top of that, the 600 makes its sporting debut bereft of either a 16-inch front wheel or a square-section tube frame.

For those who adhere to sport chic, that makes the 600, despite its FJllOO-inspired bodywork, nearly naked at the cotillion.
Discounting the 600 as a sportbike lacking the requisite racy filigree not only misses the point, though, it dismisses what might well be the best middleweight sporter for 1984. What's important with the 600 is what's in the package, not what's missing; and what's in the 600 is sound, established engineering.

The engine is based on the eight-valve Seca 550 powerplant, and is extremely compact. And, more was done to the original 528cc motor than the bore-and-stroke that brought its displacement up to 598cc. In revamping the 550's engine Yamaha engineers altered combustion-chamber shape, valve sizes, cam profiles and timing, carburetor size and airbox capacity, all to achieve one specific goal: performance. Even fuel mileage took a back seat to engine performance: YICS, Yamaha's mileage-boosting interconnected inlet plumbing, was" dropped when it was found the engine pulled stronger—although at a somewhat higher fuel-consumption rate—without it.
And the resulting powerplant does pull. Below 7000 rpm the engine offers good power for a middleweight streetbike; nothing is lacking.

Above that engine speed, though, the 600 is all sport-bike, and easily revs to its 10,500-rpm redline in five of its six gears. And in sixth, the prototype FJ600 we rode managed almost 10,000 rpm—and an indicated 125 mph—down Willow's back straight.
Just as important as engine performance is handling, and in that area the 600 gives away very little. At a claimed 415 pounds, the FJ600 is among the lightest of the sport middleweights, and its lack of excess poundage pays off in every corner.

And the 600's relatively quick steering geometry (26 degree steering head angle, 4.17 inches of trail), lets you flick the bike through those corners without muscling it—and without turning it twitchy at speed. Hauling down from speed is equally predictable, thanks to the 600's excellent triple-slotted-disc brake setup; the only flaw we found in the 600's braking was a tendency toward nosedive in full-on stopping. Overall, from ride quality to ground clearance to ergonomic layout, the 600 displays impressive performance credentials, either for closed circuits or the open road.
So, even though the FJ600 might be starting 1984 a little out of the spotlight, we're betting it won't end the year that way.