The naked gun

One of motorcycling's enduring fashions is for "retro-bikes" - those simple, unfaired roadsters whose styling harks back to the Seventies or before. Machines such as Honda's CB Seven Fifty, Kawasaki's trio of Zephyrs, and Triumph's new Thunderbird echo famous models of the past, combining nostalgia with a respectable degree of modern performance.

All of which is less than helpful if, like Yamaha, you do not have much of a superbike history worth recalling. The Japanese giant's early success was based on a string of brilliant small-capacity two-strokes. In contrast, Yamaha's impact on big-bike development in the Seventies was roughly equivalent to the Osmond brothers' influence on heavy rock music, and the firm only became a force in the superbike market long after tank-tops and flares had been consigned to the back of the wardrobe.

Maybe the Yamaha designers' opportunity to start afresh was an advantage, for the XJR1200 is arguably the most handsome of current unfaired Japanese machines. For those with good memories, its black paintwork and big, four- cylinder engine are vaguely reminiscent of Yamaha's XS1100 Sport, an overweight and forgettable brute from the early Eighties. But the new bike is a more finely honed machine whose bulges suggest muscle instead of flab.

A more recent model that Yamaha has been glad to make use of is the FJ1200, a deservedly popular sports-tourer whose air-cooled, 1188cc motor was adapted to power the XJR. The proven twin-cam, 16-valve FJ unit was livened up visually with polished tips to its cooling fins, and detuned to reduce its maximum output from 123bhp to 97bhp, the lower figure being deemed sufficient for retro-bike use.

The XJR's frame is also similar to that of the FJ, although its steel tubes are round in section instead of square, and the new bike has old- style twin rear shock absorbers in place of the sports-tourer's more modern single unit. The rest of the XJR's specification is conventional and impressive. Thick, telescopic front forks, wide wheels with low-profile tyres, and large-diameter twin front disc brakes with four-piston callipers all help give the XJR1200 an impression of performance as well as style.

It is a look that the Yamaha more than lives up to on the road, although the big, heavy XJR feels sensible rather than exciting as you settle into the fairly low seat and reach forward to the slightly raised handlebars. The upright, roomy riding position is well suited to slow-speed use and the Yamaha seems to shed much of its bulk on the move. This combines with the engine's crisp response at low revs to make the bike easy to ride in town.

However, it is on the open road that the XJR1200 comes into its own, thanks mainly to the four-cylinder motor's wonderfully strong, mid-range power delivery. Winding back the throttle, even at very low engine speeds, sends the bike shooting instantly forward with a thrilling and effortless burst of acceleration. The handlebars tug at your shoulders, the wind pulls at your neck, and behind the visor your face invariably splits into a huge grin.

Soon afterwards you slow down again, having been reminded that the human body was not designed to be treated like a parachute. Despite its detuned engine, the Yamaha has a top speed of about 140mph, but it is better suited to much lower speeds. At a more gentle pace the XJR gives a pleasantly relaxed ride, the rubber-mounted motor passing on very little vibration, and its flexibility minimising the use of the five-speed gearbox.

The big, heavy Yamaha cannot provide the handling of a lightweight sports bike, but by naked standards its chassis works well. Suspension at both ends strikes a balance between being firm enough for brisk cornering, yet soft enough to absorb most bumps. Unlike the XS1100, its notoriously wobble-prone forebear, the XJR1200 remains stable at speed and is great fun on a twisty road. Its fat tyres have plenty of grip, and the twin front disc brakes are impressively powerful.

Big, naked bikes such as this tend to be more practical than their simple layout suggests, particularly for the modern breed of low-mileage, fair- weather rider. When the sun is beating down, the lack of a protective fairing allows a cooling breeze that is welcome when you are cooking inside black leather. The strong, flexible engine shrugs off the extra weight of a passenger and luggage. And the XJR's efficient mirrors, reasonable fuel range, broad dual-seat and useful pillion grab-rail are also features missing from many modern machines.

Despite their basic specification and tendency to use components shared with, or developed from, other models, most naked superbikes are not particularly cheap. And that is certainly true of this particular Yamaha model, which costs pounds 7,629.

However, its good looks, superb engine and competent chassis do make a tempting combination. For all its humble ancestry, the XJR1200 is a retro-bike with genuine class.