Feature Bike – The Whittleton Special

July 1 2012
Classic BMW rebuilt and restored

July 2012 feature bike

Many people might claim they can improve upon fine German engineering, but actually doing so is a totally different story. Bob Whittleton, however, was as good as his word, even if it took him 13 years to finish the job.

Bob took delivery, literally, of this leftover 1977 BMW R100RS in 1978, when it was dropped off in his driveway, still in the original shipping crate.

Over the years, Bob puttered away, disassembling the bike, including the engine, right down to the last nut and bolt. Maybe he just wanted to make sure the workers in the BMW factory did a good job. After all, you can never be too cautious about another person’s qualifications and work ethic.

Bob’s objective from the start was to make the bike as light as reasonably possible and blueprint every component before reassembly.

They say that when you start a diet, you lose a lot of weight really fast and then you plateau. Luckily for Bob, he was able to unload the large RS fairing to a friend who had dropped his bike the year before, causing serious damage. Other major weight losses, totalling about 14 kg, were achieved by removing the electric starter and replacing the oversized original battery with a smaller unit that now resides in the café tail section.

A picture of the BMW R100RS handlebars and dashboard

Bob then moved on to the engine. Of course, the weight loss continued when he removed metal from the crankcase and drilled and balanced all moving components that weren’t being replaced with lighter bits. In addition to measuring and documenting every part, it also meant adding some very trick components in the process, like Carillo rods, sport camshaft, Nykasil-coated cylinder sleeves, and Mahle slipper pistons with lightweight wrist pins, just to name a few items.

Bob had good intentions during the engine’s rebuild when he installed Krauser four-valve heads for better breathing and with the hope of increased power, but this turned out to be a mistake after only 3000 km. The pushrods operated at an awkward angle, and there was so much load on the camshaft that it quickly wore and distributed metal throughout the engine.

Usually he would have sold off the original heads, but he admits that in an unusual display of common sense, he kept the original ’77 heads, so after an extensive rebuild that included resleeving the cylinders, he consulted with Tim Speigelburg, Canada’s premier Ducati tuner, about possible head work.

Photo of the front wheel R100RS“He did incredible work on the heads. Basically, those intake ports are way too big for slide carbs, so he made the intake ports smaller to increase the velocity. In the process he reangled the ports, so now the carbs are splayed outward. ” Bob said, “ He welded and bathtubbed the combustion chambers and contoured the piston crowns to produce a measured 11:1 compression ratio. Now I just have to make sure my knees are feeling okay before kick-starting the bike.”

The RS’s diet continued as the bike went together, and in total, Bob figures he was able to shave off about 41 kg from the original. When his rebuilt RS finally saw the light of day, it was unrecognizable from the original, and with the exception of the four-valve heads, it hasn’t changed much since its unveiling, mainly because it’s hard to improve on perfection. The spec sheet for the blueprinted Whittleton Special reads like a Weight Watchers’ rulebook, and is far too long and detailed to include in these few pages.

It goes without saying that the bike’s weight-loss program, the trick components and the professional workmanship that has been put into every aspect of this bike is the reason it will run a 11.4-second quarter mile at 120 mph. And with a maximum rpm of 8300 and 82 rear-wheel horsepower, this café racer has as much go as it does show.

“It won’t keep up with a modern sportbike, but for what it is, and what the rider is, it does okay,” were Bob’s parting words.


Owner: Bob Whittleton
Make: BMW
Model: Whittleton Special
Builder: Bob Whittleton
Time to Build: 13 years
Year: 1977
Builder: BMW/Whittleton
Displacement: 1000 cc
Cases: BMW
Heads: BMW/extensive rework by Tim Speigelburg
Lower End: BMW
Carburetor: Mikuni TM 38:86 Pro Series
Ignition: 1981 BMW electronic, dual coils
Exhaust: BMW 40 mm headers with Staintune 40 mm sport mufflers
Year: 1981
Builder: BMW
Type: RS close ratio
Clutch: 1981-style
Year: 1977
Builder: BMW
Final Drive: Shaft
Shocks: Ohlins Piggyback
Modifications: Steering head braced, lateral braces
Front End  
Year: 1974
Builder: BMW
Triple Trees: Stock
Modifications: Fork Brace from lower triple clamp
Front Size:  
Builder/Manufacturer: BMW/Sun/Buchanan stainless steel spokes
Tire Make and size: 110/90-19 Metzeler Lasertec
Rear Size:  
Builder/Manufacturer: BMW/Sun/Buchanan stainless steel spokes
Tire Make and size: 130/80-18 Metzeler Lasertec
Gas Tank: 23 litre /7 Police tank with tool box
Footpegs: Terrozi rearsets
Seat: Short RSS
Handlebars: Telefix clipons
  Special thanks to Tim Speigelburg for expertise and headwork

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