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‘87 BMW R100 – Skrunkwerks


Posted on April 10, 2015 by Andrew in Racer. 36 comments

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Written by Marlon Slack.

I like just about every bike featured on Pipeburn. From yard-built bobbers, lean café racers and scramblers of questionable practicality there’s always something of merit in their design and execution that warrants a closer look. But there’s a special place in my heart for performance-based bikes built with a singular purpose in mind. Products of consideration, calculation and engineering, often ridden with stupidity paraded as bravery. So today, here’s a real treat – a gorgeous, beautifully thought-out and immaculately crafted 1987 BMW R100 salt racer designed, built and raced by Adrian from Skrunkwerks in Melbourne, Australia.

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You might be surprised to know that alongside bourbon, country music and chronic obesity the United States doesn’t have a monopoly of dry salt lakes. Here in Australia we have our own large white dyno in Lake Gairdner, South Australia. Over seven hours out of Adelaide – a similarly isolated area that is also unable to sustain life – our salt lake has a much less predictable climate, an absolutely abhorrent dirt track entry road and no facilities at all. I’m friends with a few people who have made the pilgrimage over the years but I’ve never made the trip myself – being of the demographic that won’t go anywhere without 4G network coverage or easy access to organic fair trade coffee.

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This means that only the most dedicated speed freaks carefully watch the weather reports and pack up the four-wheel-drive to make the pilgrimage to the Australian speed mecca each year, leaving casual observers like myself simply turning and tipping a drink in the direction of their noble pursuit five times a day. And after 18 months of planning and building Skrunkwerks joined a throng of like-minded enthusiasts when they finally wheeled this piece of automotive art onto sandpaper-like surface of Lake Gairdner.

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Skrunkwerks had big plans for the bike when it was first started in a workshop alongside Supacustom’s Triumph Bonneville that was also being built to break land speed records. The BMW was to have a very heavily worked engine, with Skrunkwerks aiming for 110 horsepower, but due to some last-minute problems this was put aside and a R100 donk already running in his gorgeous café racer was mounted instead. Adrian aims to have the fresh engine ready for a tilt in 2016, possibly with some kind of forced induction. And I’ve no doubt that it will work beautifully.

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Because even the back-up engine is nothing to be sneezed at. Producing around 75 horsepower, it runs 38mm Dellorto carburettors, an oil cooler taken from a Bonneville, dual plugs, porting, a CR increase and a few other tricky bits and pieces to get the bike up to speed. Most notable of these is ‘Ramstein’ – the large ram air intakes you see jutting out either side of the engine. Ram air intake systems are finicky, difficult to jet carburettors to and have slim-to-bugger all gains at any speed other than flat-out. To this end the bike also had a set of huge K&N air filters ready to mount if it ran into any trouble at the lake.

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A great deal of effort has gone into suspension design, a crucial focus when riding a bike like this far faster than the original maker of the bike or the maker of the rider ever intended. The R100 runs GSX-R triple trees and USD forks at the front while the custom mounting arrangement of the Hyperpro shock marries it to the R1100RT swing arm, and a R1100S bevel drive – required for its taller gearing.

The swingarm lengthens the stock wheelbase by 100mm, with Bridgestone BT45 tyres mounted to the K100 rims on each end. With the fully worked engine, all these modifications add up to theoretical top speeds of over 150mph, thundering along at a max of 9000RPM, all the while combating rear wheel slip – said to be around 10% while running on the salt.

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It’s easy to get bogged down into the numbers while missing the sheer beauty of the bike. The fit and finish is immaculate – with some the most beautiful frame bracing I’ve seen on a motorcycle, much of which is laser cut and hidden under the chopped and shut fuel tank. The colours that have been picked are gorgeous, the welding is immaculate and the attention to detail is second to none (look at those guides for the rear brake line!).

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Like much of the engine work, the carbon fibre seat and hugger were completed in-house. And I suppose it shouldn’t come as much of a surprise, being designed and built by a man who manufactured his own tube bender and dynamometer in his spare time. And here I sit considering my spare time productive if I manage to get through half a bottle of rum and a season of Louie.

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For 2015 the R100 was entered into the MPG1000 class – 1000cc pushrod motorcycles that are unfaired and running on pump gas. Acts of God and other tribulations meant that he was to only have two runs on the salt – but still set a top speed of 128MPH (206 km/h) – only 12.6 miles (20.3 km) short of the current record. And all that from a relatively mildly worked boxer engine, which Adrian thinks still had a few more ponies to be let out with some more tuning. That’s academic though as in 2016 the bike will return to the lake with the dedicated salt racing engine he had originally envisaged. Until then the bike will return to his workshop, looking as gorgeous sitting still as it did as a blurred dart across the Lake Gairdner horizon.

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  • Jules

    There’s no front brake, was that just the case when the photos were taken, or do they run with no front brake?

    • Johnny Hillard

      No front brake is pretty normal for land speed racers. With miles to slow down, they’re pretty useless. Weight loss is the name of the game.

      • martin hodgson

        It’s also a safety issue on the salt, grab a handful of front brake and you will fold the front over and wreck a beautiful machine. And as you say, with miles to slow down there is just no need!

    • Skody McNad

      The real question is, where is the control for the rear brake? Im I missing something?

      • arnold

        Hold your right hand up.

      • The front brake lever looks to operate the rear brake.

        • Skody McNad

          got it! That makes sense.

  • John Wanninger

    This is a BMW I like. I know its purpose built, but I’d like to run it on the street.. with front brakes of course. Skrunkwerks FTW.

    • attempting land speed records on the street is probably not a good idea

      • John Wanninger

        I promise I wouldn’t…. I’m old, and ride as such…. I’m a good boy when I ride my liter bike too, which I guarantee is faster than this bimmer.

    • John Wanninger

      I promise I wouldn’t. I’m old, and ride as such… I’m a good boy when I ride my liter bike too, Which I can almost guarantee is faster than this bimmer.

    • arnold
  • revdub

    Wow. Very different and equally cool. The workmanship is amazing.

  • Hardley T Whipsnade III

    Well ! Will you look at that ! Its not a Scrambler . Its not a Bobber . Not even another over caffeinated Cafe Racer . Why ! OMG ! Its , something ! Different ! A nod to the past . A look towards the future . And better yet . Its a good something different ! Wow . Can it be true ? Does creativity still exist ? Does quality craftsmanship still matter ? Will miracles never cease ? Methinks by the looks of this creation the answer is : a Definitive . Yes ! On all counts .

  • I can’t help but wonder what it’s look like with solid matt black wheels. Even more badass, I bet…

    • guvnor67

      Hell Yer!! And a Street (legal?!) Version, stealth mounted blinkers etc, satin black headlight wiv a stainless rim, and an exhaust note to make even the Devil cry himself to sleep at night!!! I hav to see and hear this bike in the flesh of my life Will not be complete!! Damn …..

      • Like this…

        • skrunkwerks

          Very cheeky that you should take such liberties with my bike Andrew….but I like it!!

          • arnold

            Good thing Andrew is missing robin’s egg blue from his palette.

          • Apologies for my cheekiness. Now, when will you have the wheels for us to see? 😉

    • Hardley T Whipsnade III

      This bike is living proof what happens when a custom builder knowingly or unknowingly applies the age old ‘ Shaker’ theory of design to the bike he or she is building .

      That theory being ; First and foremost make it functional . Then to what ever extent possible make it beautiful without sacrificing any of its intended function .

      And yes . This bike is so achingly clean and beautiful it would almost be a crime against all things Gear/Petrolhead not to build a street version at some point . Though Andrew . Methinks the solid disc wheels would have to go . Solid discs being in direct contradiction to the overall function of a street version of this bike

  • Absolutely marvelous. Clean as a whistle.

  • Spyker May

    If you have ever been to Bonneville then your first observation will be: ‘the salt here looks beautiful’ – I bet it is worth all the tribulations and even average runs will be edged in your memory for ever.

    As per the old adage: ‘here you live more in five minutes than most people in a lifetime’.

    Not sure what the rwhp was for the 128mph run, but 110hp from this vintage of R100 will be a feat in its own, considering the original mustered around 60hp.

    The mammoth oil cooler suggest they are running an impossibly high compression ratio (as they should). Equally I am not sure what rules they are running to, but perhaps they could consider reversing the ‘heads’ – ie running the carb in front and the exhaust to the back (for some ram air effect to give that edge to the high compression).

    In any event, these guys know their stuff and all said (viz I am a nut for landspeed stuff and there is beauty in things that work well), I like it a lot – as it is and irrespective of what the slips say.

    GODSPEED!

    • Don Arnold

      Exhaust valves will overheat, keep them into the wind.

    • From chatting the Triumph Salt Racer guys, it seems that 110rwhp is what you need to get an unfaired bike like this to 150mph on the salt.

      • Spyker May

        Second that. Once took an ’05 Duc 999, with fairing and other paraphernalia stripped, rear sprocket change and only an exhaust and tuning mods (dyno ~130 rwhp if memory serves), on a salt-run – just for the fffffff… of it. Clocked a smidgeon under 160 (yawn…). This one is lower (smaller frontal area) so hunting 150 could be on the cards.

        Worked at a co in SLC at the time – the way we kept out of (mmmm or perhaps IN) trouble on weekends.

  • Workmanship, purpose, well executed and it has no pipewrap or Flintstone tires! There is hope after all.

  • looks a nice place to go if you like chips

  • Davo

    The salt lake location is actually spelt “Lake Gairdner”

  • Uwe Sentner

    Perfekte BMW ! Wow

  • The quality of the work on this bike alone is incredible, never mind the attention to detail. Hell, look at the right rear-set bracket.

  • Darrick B

    Gorgeous, the definition of ‘less is more.’ Add a headlight and front brakes, move the rear sets forward, and it would make an amazing street bike.

  • Cliff Overton

    That’s a brilliant bit of BMW there, makes me damn proud to be a part of the Melbourne bike scene and damn proud to know the writer too (latte Marlon?).

  • What an ultra-clean design! Minimalist to an extreme!

  • shalbleib

    REAL REAL pretty. Fit and finish looks immaculate!