SKRUNKWERKS SALT RACER | BMW R100 Landspeed
Words Adrian Braun Photography Luke Ray
This article first appeared in Tank Moto issue 08.
If you want something badly enough, the world often obliges. I’d been squatting a workshop of sorts in the garages of friends. I had been wishing for my own space to fill with the equipment needed to make the ideas in my head real. I knew this all hinged on finding a doppelganger. Someone similarly afflicted by the motorcycle bug with whom to share resources, ideas, enthusiasm and... the cost.
I met Ross Osborne of Supacustom fame at a classic motorcycle meet. It was his custom Triumph that told me this guy could capably execute a unique idea. Also an obsessed customiser of classic motorbikes, he too suffered workshop envy. Our minds melded, I had found my doppelganger. That same day we decided to look around for a workshop to share.
The world again obliged. I found a warehouse to rent close by. Not through the classifieds, but by fatefully knocking on the right door. Two years on and there is almost nothing we can't make with our lathes, mills, benders, welders, cutters, shutters and pot belly heater to keep the winter chill from the bones. But only possible, it should be said, with unhealthy levels of cost denial. The day job giveth and the obsession taketh away.
Salt racing was an idea implanted in my mind by my brother in law Colin Will. A long suffering motorcycling tragic, he had restored and was racing the 'Corish Norvin', a Vincent motor in a Norton featherbed frame that was famed for ripping up the record books when first raced in the 1970s. We'd planned to race the bike at the DLRA speed week at Lake Gairdner in 2005 but the event was rained out. With his salt dream unrealised, Colin tragically died of cancer in 2008.
Colin always joked that he ‘skrunked’ away in his workshop, a warpage of Lockheed Martin’s special developments team Skunk Works. I adopted the further warpage Skrunkwerks as homage to both Colin and the coolest design team in history.
Colin’s salty idea was resurrected during a chinwag by the pot belly stove one night. Both Ross and I would design, build and race our own bikes. We had eighteen months of build time before the Lake Gairdner event in March 2015. Ross, together with Paul Chiodo of Peter Steven Motorcycles, formed a team and elected to base their build on a modern Triumph Bonneville. I on the other hand had a stock 1987 R100 begging to be transformed into the machine that would carry me across the salt…
Simplicity was in mind from the outset, so the unsuspecting airhead was carved to the bone then rebuilt with only one function in mind. Any part, any feature that did not directly contribute to that singular function was deleted. The frame was stripped of unnecessary parts including the stock sub-frame. The tank hides a network of custom laser cut plates to stiffen the ‘rubber cow’s’ spine (no more high speed wobbles thanks). A GSXR 600 front end handles the pointy end, but brakes were deleted to reduce air resistance... no problem with 160 kms of salt lake in front of you to pull up on!
The rear suspension is handled by a BMW R1100RT swing arm supported by a Hyperpro shock sitting in a custom cradle. Hanging on the back of all this and tied to the frame via a custom adjustable torque arm, is a bevel drive from a R1100S which provides the taller gearing necessary for the salt (2.75:1). This arrangement also adds 100mm to the wheelbase for more straight line stability.
Wheels are from a K100 and the rear tyre was chosen for the largest outer diameter so gearing could be further increased. Fabricated supports for the rearsets help the rider stay low and lean and I had inherited a 1980s fibreglass superbike tank from Colin which was reshaped to suit this bike.
The seat was first designed in a solid modelling program from which offsets were generated and a perfect wooden replica of the seat was built. This 'plug' was then used to make a female mould in which carbon fibre was laid-up to produce the final part. A custom cantilevered rear end was then welded in place to support the new carbon fibre seat.
The R100 motor would be reworked for a redline of 9000 RPM and a target 90HP at the wheel – 60% more than stock. The hit list: 340 degree high lift race cam, short skirt high compression (11:1) pistons matched to 15mm longer than stock, light conrods with crankshaft balanced to suit. A further compression ratio increase to 12.5:1, intake valve increased to 46mm. Porting, Lectron 44mm carburetors, programmable ignition, oil cooler, lightweight valve train with generous helpings of titanium, custom tapered aluminium pushrods, modified oil pump, deeper sump, an exhaust ‘eductor’ to suck a vacuum into the case and… lots of dyno time. The inertia dyno that I’d built from scratch at our workshop really came in handy.
A feature that largely defines the look of the bike: the bull horn shaped carbon fibre airbox was dubbed 'Ramstein' and would hopefully stuff a little more mixture into the heads for a few more beans at the back wheel. The shaft drive doesn't allow the luxury of simply changing a sprocket for correct gearing. However with a five percent higher top gear, the long legged R1100S bevel drive and a large diameter rear wheel, the magic number of 150MPH could be reached at 8300 RPM. That was theoretical of course and didn’t take into account the wind resistance, slippery salt and extreme heat. I just had to assume there was enough power to push through those barriers.
Unfortunately, time ran out on the race motor build and I bolted in an existing motor from my café racer. This was only mildly modified with a 366 sports cam, some porting, 38mm Dellorto carbs, and a compression ratio increase to 9.5 resulting in 60HP at the wheel. Leaving no time for testing, the bike was completed two days before setting off on the twenty hour drive to the salt. Lake Gairdner is no Bonneville, there are no covered roads and no hotels, just raw outback with 100s of kms of red dusty road and a massive white expanse of salt at the end of it.
There’s nothing more surreal than sitting on the start line for the first time, looking down a void that disappeared over the horizon. A blinding white heat haze, sitting on my untested bike, waiting to launch into the unknown as fast as my machine would take me. The biggest unknown was the salt itself. We had heard too many stories about its vagaries and were a little apprehensive about what lay ahead, thankfully we were extremely lucky. The salt’s condition was the best it had been in years - like course sandpaper and some of the more powerful machines actually ran the risk of shredding tyres.
The timed mile was between the 2nd and 3rd mile markers and as I hit the 2nd with throttle wide open, the bike felt planted and the engine sang without hesitation as I asked it to sit beyond its red line for far longer than it should (there were more than a few blown donks that week). In an empty landscape with no frame of reference, there’s little to hint at your speed except the 3rd mile marker which came into view then quickly vanished behind. It was an experience that will stay with me forever.
The bike's DLRA class is MPG 1000 (A modified 1000cc naked bike with a pushrod engine running on pump fuel). The Australian record in this class is 140.6 MPH (226 km/h). This year, with a motor not much more than stock and a 7k redline, a top speed of 128MPH (206km/h) was managed. And Ross? He cracked the Australian record in his class! A fantastic effort.
So, Colin and I have unfinished business and work continues on the airhead race motor in readiness for the 2016 DLRA Speed Week at Lake Gairdner where the record waits in the heat haze, sitting squarely in our cross-hairs.
Follow Adrian @skrunkwerks.