1937 BMW R5 – Krautmotors
Written by Martin Hodgson.
Whatever the sport, the hobby or industry for it to have long-lasting success and be something others are drawn to like a moth to a flame you need big personalities with an unwavering passion and endless enthusiasm to drive it forward. In the custom bike scene of Germany one such man is Rolf Reick, a.k.a. Mr Krautmotors, who is involved at every level and never seems to run out of new ideas. The graduate industrial designer and head of a school for product design and multimedia in Mannheim can be found doing everything from organising events, to printing t-shirts and building bikes, but what truly gets his own heart pumping is the increasingly popular sport of sprint racing. Pitting man and machine against one another over an 1/8th mile drag race, Rolf comes to the party with his Krautmotors No. 5, a 1937 BMW R5 packing bulk Bavarian BHP.
With the R5 originally released in 1936 and its bloodline still continuing strong to this day, 2016 has been a special year for the model as it celebrates its 80th anniversary. So enthusiastic about the model are BMW HQ that they released a one-off custom called R5 homage and chose Rolf’s No. 5 to be front and centre as the poster bike for the BMW backed 2016 Pure and Crafted Festival in Berlin. Head of design at BMW Motorrad, Edgar Heinrich explains: “The R5 was a masterpiece at its debut.
The clarity of its lines and the elegance of the proportions gave the machine a distinct profile and set it apart from the competing field of motorcycles. This is one of the most beautiful motorcycles in the history of BMW.” And the big Bavarian company felt that the Krautmotors machine represented that to perfection. But it has been a journey of ups and downs for Rolf and his custom racer and before you is but the latest evolution of this incredible machine.
When Rolf bought the bike it belonged to Michael Ahlsdorf, editor in chief of Germany’s Bikers News and was a mild custom that Rolf intended to use as a road cruiser, kept relatively original “Thus avoiding trouble with overenthusiastic police officers.” It’s a story we’ve heard a thousand times before and his infectious enthusiasm for customisation came through when he casually swapped out the 24hp engine for an 80hp fire-breathing monster.
Rolf explains the reason behind the engine change “I replaced the motor to take part in a race I invented a few years ago and organize ever since. The race is called ‘Starr Wars’ – a sprint race solely for bikes with rigid frames.” He had intended on switching back to the stock motor after the event but the racing bug had bitten and the bike was to become an 1/8th mile specialist with a visual nod to the factory competitions machines of the ’40s. But early in No. 5’s racing career an opponent “closed the door” on Rolf at the end of a fast straight and both rider and machine hit the deck each suffering considerable damage.
It was time for a rebuild and it all starts with the long and low 1937 frame that feeds Rolf’s appetite for rigid frame racing, strictly sans rear suspension. Sitting up on the backbone is a post war R51/3 gas tank that replaces the stock unit that was destroyed in the accident. The gas cap has been replaced with one wearing the Starr Wars racing series logo and the front of the tank received some “gentle” hammer work so as to clear the new suspension. Wanting to create a sleek-looking design but not obscure the view of the engine Rolf went hunting for a fairing that would suit, but with the modifications he had in mind nothing came close to fitting.
“That was when all of a sudden the brilliant idea hit my mind to put the fork right through the headlight cutout of a classic fairing.” to compliment the look and with aluminium in hand he started to sculpt his own side coverings, keen on keeping it as tightly tucked to the frame as possible and in line with the old school theme. Then the two pieces were rubbed back and given a coat of classic BMW racing Black with the Pure & Crafted Logo painted by Christian ‘Chiko’ Rupcic.
Poking through the fairing is one of the standout features of the bike; the raw steel girder forks a fairly unusual sight at the drag strip. Weight transfer is key in an 1/8th mile run, planting the rear for a good hook up off the line, but with a rigid frame this can easily cause the tyre to shake and the girder keeps things flat letting the tyre do the work. Rolf took the forks from a trike and then shortened and narrowed them as well as switching the linkages to the inside for a sleek finish. The stem arrangement was modified to allow it to fit into the old BMW headstock and a custom set of risers hold chrome clubman bars that let Rolf get low and out of the wind.
Having previously run a telescopic fork before the crash the front wheel assembly survived and has been adapted to fit with an 18 inch rim laced to a Yamaha SR drum brake hub. Out back there is obviously no suspension to speak of being a rigid frame but a generously sprung Denfeld saddle seat takes care of the worst of the bumps and vibrations. However it’s that rear tyre that really dominates proceedings and lets you know No.5 means business, an M&H-Racemaster slick providing all the grip you could ever need.
To say that the engine is the key component in drag racing is an understatement of epic proportions and given the bike started with a 1937 engine producing just 24bhp it’s clear that an upgrade was in order. Rolf didn’t muck around and went straight to the best, Dirk Scheffer from Edelweiss Motorsport who has a reputation of extracting insane levels of power out of 2 valve BMW’s and doing it in a reliable manner. While it may look like a relatively stock BMW engine from the outside the internals are all business resulting in 1100cc that pumps out in excess of 100bhp, dyno proven.
The engineering is exceptional, I beam rods are chosen for their reduced reciprocating mass and their elasticity over an H beam that places less lateral force on the piston pin. Combined with the lightweight Edelweiss Motorsport pistons and custom camshaft this allows the engine to rev faster and higher despite its considerable increase in swept capacity.
Another special trick that is vital to the maintenance of a racing engine is the reusable aluminium head gaskets that not only provide improved thermal efficiency but also allow Rolf to pull the heads during a race meeting to diagnose any engine issues without having to have an enormous stash of replacements on hand. Despite its obvious air-cooled notoriety the R series engine benefits from a front mounted oil cooler that has been placed front and centre and utilises braided lines and race fittings.
The most obvious external sign that this is no 20hp wheezer is the pair of thumping Dell’Orto carbs measuring 40mm a piece. The accelerator pump equipped units provide the fast fuel supply needed in 1/8th mile drag racing and fitted with open velocity stacks there is zero impediment to vast quantities of air being sucked into the thirsty donk. Expelling the spent gases is a beautifully handmade stainless steel exhaust system that merges at the rear of the engine before exiting out of a low slung chrome muffler.
Controlling all that power Rolf relies on the seat of his pants and a fast action throttle that hopefully stays pinned for the entire run should the slick hook up. Clutch and brake levers are all the accessories that are needed to get the bike down the track, although a small headlight peaks through the forks should night-time racing be on the cards.
Having recently competed at the ever popular Glemseck 101 near Stuttgart the engine didn’t disappoint but further strengthening of the frame was the key take away from the meeting, but that will have to wait for the European winter, “Right now I’m preparing for the German Intermot in Cologne to take part in the last Sultans of Sprint Race in October this year. Keep your fingers crossed for No. 5.” Fingers and Toes we promise Rolf, but most of all we’ll be cheering on Mr Krautmotors himself whose enthusiasm and hard work is taking the hobby and sport we love to new levels.