For most of the 20th century BMW earned a reputation for building reliable, if somewhat stodgy, touring motorcycles. All that changed in 1974 when BMW introduced its first superbike: the R90S. Higher compression pistons (9.5:1), 38mm Dell'Orto accelerator-pump carbs and twin disc brakes distinguished the S from the more-pedestrian Beemers-but what really set the R90S apart was its looks. The S featured a sleek seat with a plastic hump, a curvaceous bikini fairing and striking two-tone Silver Smoke paint.
For 1976 the R90S received drilled brake rotors and a two-tone color option known as Daytona Orange, in honor of Steve McLaughlin's and Reg Pridmore's first and second place finishes at the first AMA Superbike race in Daytona. Pridmore went on to win the 1976 AMA Superbike Championship with his Butler & Smith-modified R90S, cementing the bike's place in history.
The last model year for the R90S was 1976. The R100S that replaced it in 1977 was down a couple of horsepower from the original despite an additional 82cc, mostly because of a swap to Bing carburetors. While the Dell'Orto carbs were relatively troublefree, they weren't very fuel efficient.
When shopping for a used R90S, originality determines the value. Many collectors won't buy a bike that doesn't have original paint. If the fairing is missing or has been replaced by an aftermarket unit, forget about it. Clean, original bikes go for $5000-$7000; subtract at least $1000 for a bike without original paint.
Many 898cc Beemers manufactured for 1974 suffered from difficult shifting, but this problem was corrected by 1975. Most early bikes have already been fixed with a kit that modifies the shift fork, so if a bike shifts well you should have no problems. Be cautious of bikes with the optional kickstart, though, because the kick lever has a tendency to sheer off important bits within the transmission.
There will be some wear on the valve seats because of burning unleaded fuel, but this is not as great of a problem as it would seem. Just ride the bike until you start to notice the exhaust valve clearances closing up abnormally fast, then install new valve seats and exhaust valves. You can get by with lapping the intake valves, which should cost around $350-$400. That's less than the price of a set of tires for a modern sportbike. The R90S is a practical classic reliable enough to actually ride every day. -Darwin Holmstrom