Retrospective: BMW K1: 1990-1993

photography by Jim Cyran

[This Retrospective: BMW K1: 1990-1993 was originally published in the January 2011 issue of Rider magazine]

This was the second attempt by BMW at making the “Flying Brick,” as the K100 was fondly referred to, palatable to the market, but it did not fare too well. What the K1 did have going for it was looks, outstanding looks, one of the most fully faired (seven pieces!) sporting motorcycles ever seen, half the front wheel covered by another two pieces of plastic, all done up in the brightest red possible (or midnight blue), with brilliant yellow K1 graphics matching the yellow wheels. A visual knockout! And BMW claimed less drag on the K1 design than on any other mass-produced motorcycle.

Not that this elaborate a fairing had not been done before, as with Erik Buell’s RR1000 and Moto Morini’s 350 Dart, both appearing in 1987.

But what exactly was the K1 supposed to do? It certainly wasn’t the traditional BMW sport-touring bike, as there was only some small optional soft-luggage to give it carrying capacity. Was it a superbike? Heck, for two-thirds the price of a K1 any of the Japanese sport tourers (emphasis on the “sport”) could stay well ahead of the BMW. But that, maintained BMW executives, was not the point. This was a German superbike, which would stand on its own merits. True, the Japanese seemed obsessed with lap times and dyno ratings, and were more involved in internecine competition rather than worrying about the Europeans.

BMW had been obsessed with not mimicking the Japanese…not building a transverse-mounted in-line four. So the Bavarian-based company had come up with its own version of the in-line four, laid longitudinally on its side. According to legend, BMW had wanted to phase out the old-fashioned air-cooled boxer and hoped to do this with the K100 that was introduced in 1983. Unfortunately, the Flying Brick was no great sales success, as it did have problems, the major one being heat. The BTUs given off by the cooling system could toast a rider’s lower extremities.

The same engineers also seemed to forget that the sidestand was on the left side, the same as the cylinder heads. Leave a K100 parked for a while on an angle, oil would seep past the piston rings into the combustion chambers, and on start-up the bike would look like a smoke-screen device. After a few years (1989) the smoking situation was taken care of by using a Citroen-based system of arranging the piston rings to ensure the oil would not get through—maybe just a little did.

And nobody could deny that the slow-revving engine was a bit on the stuffy side of exciting.

It soon became obvious that the K100, and its RS and RT siblings, were not going to be great sellers, while the demand for boxers stayed strong. What to do. Give the motojournalists and the buying public a real shot to the old eyeballs, and improve performance. The crankcases and slightly undersquare cylinders (67mm bore, 70mm stroke) of the K1 were the same as the K100, but the head was quite different—with four valves per cylinder. The compression ratio was increased from 10.2:1 to 11:1, and a couple of pounds were shaved off the crankshaft to allow the engine to spin a little faster. The old Jetronic fuel-injection system was also replaced with one called Motronic, designed to more quickly react to the half-dozen inputs, from engine load to altitude.

Naturally an American magazine immediately strapped this jolly red giant to a dyno and measured rear-wheel horsepower at about 83, which was nothing exceptional…about 25 ponies less than a Kawasaki ZX-10.

The chassis had also been changed, though not drastically. The tubular frame had been beefed up a bit, and the conventional nonadjustable fork with integrated brace, complements of Marzocchi, used progressive damping and offered 5.3 inches of travel. It also had less rake at 26.5 degrees, a degree less than the K100, and half an inch less trail. The K1 suffered from limited steering lock, with a U-turn requiring more than two lanes to effect. A steering damper was hidden under all the plastic.

At the back was the new Paralever, a single-sided swingarm and driveshaft that had been used on boxers but never a K-bike, which was a commendable approach to reduce the “jacking” effect of shaft drive. A single Bilstein shock, with preload adjustability, gave 5.5 inches of travel. One downside of the Paralever was that it extended the wheelbase almost 2 inches.

The aluminum three-spoke Italian FPS wheels were unconventional in that the back wheel was 18 inches in diameter, the front, 17. A fat 160/60 radial was mounted on the rear, and a 120/70 on the front. The front wheel had a pair of floating 305mm discs with double-action four-piston Brembo cali­pers, the rear a single-action Brembo with a 285mm disc. All bikes for the American market came with the latest anti-lock brakes. The K1 weighed in at a shade over 600 pounds with five gallons of gas in the tank.

Throw a leg over the saddle, at a nominal 30-plus inches; a small tailpiece could be removed for a passenger, but the bike was not really intended to coddle a pillion. Ignition on, button pushed, and a muted noise came out of the short muffler on the left side. Unseen was a large collector box under the transmission. Click into first, and a smooth clutch take-up got the K1 rolling. The handlebars were at a good sport-touring height, not too low, but the footpegs were set rather far back, more than 5 inches farther than on the sporty K100RS—very un-BMW. It was a super-sporty riding position, and the fairing coverage was more for speed than touring comfort.

The engine buzzed slightly over 5,000 rpm, which most riders could happily ignore but some found irritating. On a smooth road the K1 could easily cruise at 120-plus mph, and it did quite well in the twisties, despite its more than 5-foot wheelbase. Its weak point was on bad roads, where the suspension was often thought to be “lacking” and cornering clearance just adequate.

The last year for the K1 was 1993, also the first year for the new K1100RS, with the engine bored out to 1,092cc. Buyers appreciated the RS fairing and saddlebags. About 7,000 K1s were built over four years.

Then in 2004 BMW showed its new K1200 with the transverse-mounted in-line four—just what the company had been trying to avoid 20 years before.