Race tech: Jawa ice speedway

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Race tech: Jawa ice speedway

Race tech: Jawa ice speedway
circular saw

At first glance, only the razor-sharp spikes inspire awe on the ice speedway motorcycles. But the current Grand Prix machine of Vice World Champion Franz Zorn also has a high-tech interior to offer.

Thomas Schiffner

02/13/2001

When the four of the World Cup stars thunder across the smooth parquet, wheel to wheel into the curves and force their machines into adventurous inclines of up to 70 degrees, the ice speedway fans click their tongues. Non-insiders, on the other hand, are frightened, and they wonder how this can all go well for God’s sake.
To ensure that everything goes well, the motorcycles are equipped with razor-sharp spikes. 290 of these 28 millimeter long steel nails claw into the ice ?? 120 are screwed onto the front wheel, 170 onto the rear. Each pilot builds his own tires and arranges the nails exactly according to his ideas and needs ?? behind closed doors, according to a top secret house recipe.
As spectacular and tingling as the action on the slopes is, traditional, if not to say out of date, the technology of the ice machines presented itself for decades. Even in the third millennium, the puristic rail sport regulations still deny the ice speedway cracks many current achievements such as four-valve engines or fuel injection. And brakes are still taboo in the Eisoval, but strictly speaking, they are not necessary either. Because the high-compression single-cylinder offers an enormous braking effect when the pilots briefly turn off the gas before cornering at 120 km / h.
Otherwise, today’s machines are based on the Czech ice motor monopoly Jawa but not much in common with their antiquated-looking predecessors from past decades. The modernization of the ice scooter is thanks to people like the Finnish inventor Vejo Tuoriniemi. In the mid-1990s, he took an example from the speedway and long-distance track scene and no longer put the compact, 27 kilogram single-cylinder engine standing, but lying down in the chassis. At the same time, a change had taken place in the chassis: the Jawa rigid frames, which until then had been completely unsprung at the rear, according to the old fathers’ tradition, were given rear suspension with central struts. The pilots were finally able to adjust their motorcycles for the different track conditions. They not only change from ice runway to ice runway, but also on the same oval, depending on the duration of the race, time of day and climate.
Six years ago, Harald Mobmer from Trauchgau in the Allgau thought about further ways to improve the motorcycles and changed the chassis geometry so that the center of gravity of the machine was shifted down as far as possible. Because many ice skaters had problems with the unwanted wheelies at the start. Mossmer’s solution to also install the engine horizontally moved the center of gravity of the engine and thus the overall center of gravity to the rear, which was not what the inventor wanted. A remedy was to extend the wheelbase by 70 millimeters. Following this example, the machines of the competition have meanwhile also become somewhat longer.
The undercarriage of the reigning vice world champion Franz Zorn from Austria is the latest litter from Harald Mobmer. The methanol-fired engine hangs at an angle of 27 degrees in the aluminum sheets that are flanged to the main frame. The White Power spring strut for the rear suspension is located under the single cylinder between two additional sheets. At the front, Zorn’s motorcycle is cushioned by a specially prepared upside-down fork, also from White Power, supported by an Ohlins steering damper.
Franz Zorn, 30 years old and currently the best German-speaking ice acrobat, has consistently developed his two competition motorcycles together with Harald Mobmer. Around 60,000 marks were invested in the basic machines, which were traded quite cheaply at a basic price of 9,000 marks each for improvements to the frame and engine as well as the attachment of various lightweight components. Akront rims, fork sliding tubes coated with titanium nitride and a carbon fiber fairing weighing 2.9 kilograms ensure that Zorn’s ice-cream bomb is only one kilogram above the weight limit of 110 kilograms.
Former dirt track runner-up world champion Klaus Lausch is preparing the 500 cc four-stroke engine based on Jawa. Because of the two-valve requirement in the ice speedway, the possibilities for increasing performance are limited. Lausch condenses the alcohol burner to 14.5 to 16 to one. The single cylinder has around 53 hp and rotates up to 10500 rpm. “At even higher compression levels, the engine brakes itself at some point because of the extreme heat development,” explains the Upper Bavarian, who built his own pistons and connecting rods, crankshaft needle bearings in silver-plated cages and conical valve springs into his KLM engines and also designed the flat slide carburetor himself. With three to four camshaft versions, the performance characteristics best tailored to the driver are worked out.
Since Jawa competitor GM does not build two-valve engines in series, there is no alternative to the Czech monopoly in the ice speedway. Until now. Because Lausch has built two two-valve versions of its own four-valve speedway engine called »Vision«, which Franz Zorn is to test exclusively. If successful, the single goes into the Grand Prix. The 2001 world title would be desirable? and anger cannot be ruled out when it comes to driving skills.

bike data

Air-cooled single-cylinder four-stroke engine, an overhead, chain-driven camshaft, two valves, dry sump lubrication, 1 oil pump, fuel: methanol, bore x stroke 85.0 x 87.0 mm, displacement 498 cm3, power (depending on the compression ratio) 53 hp at 7000 / min. 34 mm KLM flat slide carburetor, primary drive via chain, external two-speed gearbox with multi-plate dry clutch. Chassis lattice frame with integrated tank, white power upside-down fork, slide tube diameter 43 mm, spring travel 100 mm, two-arm swing arm made of steel, white -Power central spring strut with lever deflection, spring travel 30 mm, no brakes, tires 2.75 x 23 at the front, 3.00 x 21 at the rear, 290 steel spikes each 28 mm long (120 on the front wheel, 170 on the rear wheel). Dimensions and weight, wheelbase 1550 mm, seat height 850 mm , Dry weight 111 kg.

Regulations

Roundabout, always around to the left: The rules of the game in the Ice Speedway World Championship are as simple as extreme winter sports are clear. An event consists of 20 or 24 races, so-called heats over four laps each. The artificial or natural ice slopes are between 300 and 400 meters long. 16 pilots take part in a race, everyone against everyone is the motto. Four drivers start per heat and receive points for their placement: three are awarded to the race winner, two for second and one for third. The four final heats are all about championship points. The drivers compete for positions 16 to 13, 12 to 9, 8 to 5 and 4 to 1 according to their counters achieved to date. In the 2001 season, the individual World Championships will be held in four Grand Prix events. The German GP will take place on March 17th and 18th in Berlin-Wilmersdorf.

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