From the factory, BMW’s R100S produced between 65-70 horsepower at the crank, depending on the year of manufacture. Thanks to Mikuni flat slide carbs, Krauser heads, and tuning by San Jose BMW back in the late 80s, this example puts down 74 horsepower at the rear wheel. Even better – the seller claims to have a complete service history for this hot-rodded classic BMW.
Krauser’s 4 valve heads are very distinctive, and many were used on the Krauser MKM1000 – a limited run of motorcycles which were the most powerful stock airhead produced at the time. Krauser claimed that their 4 valve heads would bump up crank horsepower to 82 and would increase compression to 10.2:1. The head kit included a set of Mahle pistons and rings, and the heads developed a reputation for reliability issues because some riders didn’t realize the kits weren’t ready to go out of the box. For more on these heads, check out this short profile on Motorcycle Classics. These are definitely for airhead fanatics, as the dollar to performance ratio would make no sense to a modern sportbike rider. 5 years ago a set sold on eBay for $2,600. 10 years ago a ‘new in box’ set sold for $4,159!
This bike has just 25 miles on it since 2007, it has spent the last few years on display at a store. Someone needs to get this back on the road. The seller thoughtfully has a photo album with service records, dyno sheets, product manuals, and more here on Google Drive. Find this R100S for sale here on ADVRider (registration required) for $14,000 in Jacksonville, Florida.