In the late 1970s, BMW’s trademark Boxer was on the ropes. In addition to tightening emissions regulations threatening the old slugger, a horsepower free-for-all had just broken out among the Japanese, and without a four-cylinder contender BMW was relegated to the undercard. The Bavarian propeller-heads had to come up with something newer, cleaner, and faster. The result, an inline, water-cooled four, hit flat-twin traditionalists like a haymaker between the eyes and launched BMW into a new era of multi-cylinder powerplants. One of the first fours from BMW, the K100RS, remains one of the company’s sleekest and sexiest bikes ever.
Not content with merely breaking the Boxer mold with a four, BMW laid the 987cc engine on its side, with the head on the left and the crankcase on the right, positioned longitudinally in the frame for less power loss from crankshaft to driveshaft. The layout kept the weight low—though many riders still complained the bike felt top-heavy—and simplified maintenance. Bosch LE-Jetronic fuel injection replaced the carburetors that had been standard equipment on Boxers. BMW boffins preferred two valves per cylinder rather than four, and yet the brick engine put out 90 hp, transferred to the road through the Compact Drive System that debuted on the K series.
Initial impressions of the bike were favorable if not wildly enthusiastic. The riding public took to the new design slowly but eventually warmed to it, though the subsequent introduction of a three-cylinder engine in the K75 threw a spotlight on the K100 series’ vibration. The K100 engine might not have run hot, but the same couldn’t be said for some riders whose thighs were roasted by the blazing heat pouring off the engine. This issue was resolved eventually, and the K100RS took its place as BMW’s sport-touring flagship, gaining a reputation as a solid performer and an able accomplice with a dash of style, a sporty seating position, and optional hard bags.
Those in the know say if you’re looking for a used BMW K100RS, you should go after one that’s been ridden regularly and comes with complete service records; seldom-used models with spotty paperwork seem to develop problems that all come out when the bike returns to service. There’s a weep hole under the front of the engine; if oil or coolant appears to be leaking, the oil pump and/or water pump are suspect. Another weep hole in the back of the engine case warns of a bad rear main seal or forward transmission seal.
Lateral movement in the rear wheel means possible final drive problems. Check to be sure the drivetrain splines have been lubed regularly. Front wheel bearings and steering head bearings should also be inspected for clicks or notchiness. Cracked exhaust pipes can make the bike run hot. High mileage shouldn’t stop you from considering well-cared-for examples. Used prices are on the low side even for good ones, and even though some Boxer purists still turn up their noses at its brick engine, the K100RS is a proven sport-tourer that threatens to emerge as a bargain classic in coming years.
Great looks, solid performance, attractive buy-in price.
Vibey engine, excess heat, modest power, leisurely acceleration.
Fluid leaks, little or no regular maintenance.
BMW’s breakout hit of the 1980s still draws crowds today.
1985 / $2,550
1986 / $2,650
1987 / $2,760
1988 / $2,845
1989 / $3,220
1991 / $3,360
1992 / $3,475
1987–1994 Honda Hurricane 1000
At the beginning of the jellybean-styling craze came Honda with the fully faired (and we mean fully) CB1000F, called the Hurricane for the first few years. A powerful, smooth, comfortable sportbike, it replaced the short-lived VF1000F V-4 and was the top rung until the CBR900RR appeared in 1992. We’d call the Hurricane a sport-tourer today.
1988–1995 Kawasaki ZX-10/ZX-11
Even back in the late 1980s Kawasaki was pushing its performance heritage and dropping the Z-1 name wherever it could. Good thing the ZX-10 was up to the association. Using an engine based on the Ninja 900, the ZX-10 (and by ’91 the ZX-11) was prodigiously fast, surprisingly comfortable, and even remarkably fleet of foot.
1984–1996 Yamaha FJ1100/1200
As its competitors brought liquid-cooled engines to the category, Yamaha soldiered on with the FJ1100/1200 series, whose air-cooled, inline-four carried on predecessor XS-11’s incredible torque output and turbine-like smoothness. What started as Yamaha’s top-line liter-class sportbike became a sporty ST by the time the FZR1000 debuted in 1987.