XJ 650 Maxim

Although other makers had dabbled with the cruiser get-up laid over basic Japanese four-cylinder motorcycles, no other manufacturer had made the million-dollar commitment: design a brand-new four-cylinder, and build it specifically as a special — at Yamaha the special became the standard.

For stoplight aggression, the Maxim air-cooled, twin-cam 650 engine housed in a sturdy, cross-braced duplex steel tube frame was a genuine mid-12 quarter-mile streaker. The engine looked lithe and athletic too; Yamaha made it narrow by locating the alternator piggyback—behind the cylinder block and above the gearbox rather than hanging the works on the end of the crankshaft. The Maxim had another amazing feature for a motorcycle touted as a high-performance piece: shaft drive. Contemporary reports praised the Maxim's performance and braking. Criticism was aimed at engine vibration and under-damped suspension. Notwithstanding the minor gripes, the Maxim sold well. Succeeding Maxim models were refinements; the 1982 Maxim 650 had a more comfortable cut to its handlebar, an air-adjustable fork, and a more luxurious seat. Along the way, the Maxim earned a reputation for bulletproof reliability and durability, even surviving the indignities of turbocharging in its XJ Seca incarnation — An XJ650 Seca Turbo was featured in the 1983 James Bond film Never Say Never Again. With a small set of upgrades the Maxim 650 is a capable sport-cruiser today.

Many owners add braided-steel brake lines, progressive fork springs, upgraded brake pads and tapered roller bearings for the steering head.
Cycle magazine said in 1982 "Three years later, after the wide proliferation of special styling, it's easy to forget what a landmark bike the Maxim was…The 650 was striking, controversial, sensational, and wildly successful in showrooms. Other companies have produced bodacious knock-offs of the 650 Maxim, imitations that suffer from excess. It's too bad the Maxim was obscured when manufacturers blanketed the market with cruisers. A decade down the road, the Maxim may well be a genuine classic of the 1980s — a bright idea that stood the test of time."
Yamaha's Maxim 650 ad said, "It's hard to believe one motorcycle could be so fast, so light, so lean, and so beautiful.". Also listed as the lightest and narrowest 650 bike available at the time, with the widest rear tire in its class.

The 1980-'83 XJ650 Maxim combined an air-cooled, 653 cc DOHC 2 valves per cylinder transverse inline-4 engine and shaft drive. These days, shaft drive is reserved for big bikes, and air-cooled fours have all but disappeared thanks to tightening emissions standards. And unlike the Suzuki GS650 competitor, the Yamaha engine employed a one-piece crankshaft with plain bearings and placed the alternator and starter behind the engine to minimize width. A chain drives the two overhead camshafts, which used shim-and-bucket adjustment. A second chain drives the oil pump located in the crankcase, while a third (Hy-Vo) chain spins the alternator. The power unit is fed by four Hitachi constant velocity carburetors and lit by electronic ignition. Four-into-two headers extracts the waste gases, which exit through two shortened mufflers. With regular maintenance, these engines live on longer than most people would expect. Though the lack of liquid-cooling will affect engine life in the end, it does add to the bike’s simplicity.

Hypoid gears and a shaft turns the rear wheel, with the shaft housing forming the left side swingarm. The shaft drive is lighter and smaller than conventional shafts, and with proper greasing lasts far longer than several chains and sets of sprockets, not to mention the lubing intervals are far longer.

Performance

Performance was in line with other 650 cc and 750 cc Japanese machines of the day

Top speed = 128 mp/h

Standing-start quarter mile = 12.6 sec at 107 mph (172 km/h)

Motorcycle average gas mileage = 47 mp/g

Power = 71 hp (51.8 KW) @ 9400 rpm

Torque = 42 ft. lbs (57 MN) @ 7200 rpm

Suspension = Front: 36 mm Air assisted telescopic forks, 147 mm wheel travel
Rear:5-way adjustable spring preload, 97 mm wheel travel

Tires = Front: 325-H19 (100/90-19), Rear:130/90-H16 (130/90-16)

Compression Ratio = 9.2:1

Bore/Stroke = 63 х 52.4 mm

Source: http://hem.passagen.se/nmj/xj650.htm http://www.motorcyclespecs.co.za/model/yamaha/yamaha_xj650_maxim.htm http://wiki.answers.com/Q/Spec_sheet_Yamaha_seca_650_1982

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