BMW launches dirt bike

After a very long wait and nearly as much pre-publicity as the second coming, BMW's first pukka dirt bike, the G 450 X has landed locally, priced at $12,450.

The single-cylinder machine is a completely new design for the firm, which has gone to extraordinary trouble to make sure it has been seen battling its way through enduros and cross-country events around the globe, and getting some respectable results along the way.

Its most recent appearance in Australia was for the Four-Day last April, with former world motocross champ Joel Smets putting it through its paces.

Here is the factory blurb on the bike.

$12,450

The BMW G 450 X is a brand-new development with a strong competition focus that uses technology, high performance and light weight to achieve its goals. It was designed from the ground-up for competition.

Tough, demanding development programme.

Elite enduro racing places an enormous stress on materials.

During development, the G 450 X required non-traditional methods to be applied to ensure it was ready for its role as a winning enduro racer.

Testing included the toughest enduro environment with near impossible hill-climbs, freezing cold and extreme heat, water crossings and continuous racing in extremely dusty, rocky and muddy conditions.

The machine had to be able to withstand all these conditions reliably and over a sustained period. Rarely are machines developed to be this tough.

The testing programme primarily included real-world competition as well as numerous bench tests and trials on special test tracks.

From the outset this required the G 450 X prototypes to mix it with the best of the best in the World Enduro Championships, where the slightest weakness of rider or machine can spell defeat or failure. Long-term trials in rough terrain in both Spain and Italy rounded off the overall programme. Only then was the go-ahead for production received.

The intake valves for example, are operated by follower arms; the outlet control is implemented by bucket type tappets. It's a space-saving configuration that works at high engine speeds.

Optimum performance that meets the requirements of the Euro III exhaust emission standard is achieved by fuel injection with oxygen sensor regulation and a dual throttle valve system which ensures that the engine reacts more sensitively to throttle position.

The crankshaft and conrod are fitted with roller bearings and the weight-optimised two ring piston is forged. A balance shaft effectively reduces the vibrations typical of a single-cylinder engine.

The primary coupling sits directly on the crankshaft and is configured as a wet clutch. Unlike conventional concepts, the BMW G 450 X clutch is considerably more compact and has a smaller diameter with the same number of discs. Contrary to conventional geared-down clutches, this is possible because the clutch only needs to transmit a correspondingly reduced torque on the transmission input shaft. The clutch is cable operated for optimum performance, adjustability and lightness.

The engine is fed with oil by a wet sump lubrication system. Two oil pumps, a pressure pump and a suction pump use the same oil to lubricate the gearbox and the crankshaft. The two integrated oil sieves and oil filter are easy to access from the left side of the engine for replacement. The volume of oil of approx. one litre can be checked via an inspection glass.

An intermediate shaft with integrated ventilation function transfers the power from the crankshaft to the gearbox and means that the crankshaft of the G450X engine turns anti clockwise.

The cylinder is tilted forward by approximately 30 degrees, enabling the centre of gravity to be moved in the direction of the front wheel thereby benefiting the suspension. A further advantage of tilting the cylinder is the creation of space for the intake air ducting that can now come vertically from above and virtually straight down, promoting optimum performance.

The engine of the BMW G 450 X runs a compression ratio of 12: 1 (on PULP) and uses an electric starter thanks to a powerful battery and highly reliable fuel injection. An automatic decompression function with a centrifugal force valve lifter reduces the power demanded by the starter.

Even when the machine has to travel for longer periods at higher revs in difficult and slow off-road sections, the engine is never excessively thermally loaded thanks to its large-volume, single-piece water cooler. A thermo fan provides sufficient air flow rate at low air flow speeds.

The exhaust system is made of stainless steel and aluminium and the catalytic converter is fitted in the silencer.

Despite the powerful alternator and electric starter, the high-performance engine of the BMW G 450 X weighs in at close to the average of its competitors, (at less than 30 kg).

The engine produces 38 kW (52 hp) at 9,000 rpm and 44 Nm of torque at 7,800 rpm when the Power Up plug is installed. Without the plug installed nominal power is 30 kW and 42.8 Nm of torque at the reduced levels of 7,800 rpm and 6,500 rpm respectively.

The main consideration in the geometry and overall configuration of the chassis was to meet the especially high demands of off-road racing. The results are excellent properties in rough terrain with ease of handling, great manoeuvrability and extreme tracking stability.

Innovative frame concept.
The frame layout is based on know-how from competitive racing and attendant research and development work.

The knowledge gained from earlier rally sport activities was also incorporated. The frame of the BMW G 450 X is a completely new development that differs in principle from all the machine's rivals. In the main it consists of thin walled, but high-strength stainless steel precision tubes and is welded to the node points with specially forged parts. No additional surface treatment is necessary. The entire main frame weighs a mere 8.6 kg and boasts excellent stiffness properties.

The lower section of the frame tubes run directly from the swing arm pivot point straight to the steering head. The upper section creates a direct connection between the suspension strut mount and steering head.

The wheel forces are braced centrally on the frame over the shock absorber so that the light sub-frame is bolted to the main frame and is formed by aluminium square profiles and only needs to bear the weight of the rider.

This layout enables the optimum flow of force, requires minimum use of material, thus allowing a hitherto unrivalled ratio of rigidity to weight.

The 18-inch rear wheel is suspended in a robustly dimensioned swing arm made from aluminium square profiles which supports a directly linked Öhlins shock absorber with a generous travel of 320mm.

This high-quality shock absorber features pre-load adjustment as well as tool-free compression and rebound damping adjustment.
The front wheel is located via 45 mm upside-down Marzocchi forks that absorb even the roughest bumps. Spring travel is 300mm and is also fully adjustable for compression and rebound damping.

A powerful brake system with a twin-piston floating Brembo calliper ensures the G 450 X stops fast. The single front brake disc is 260 mm in diameter, while the rear measures 220 mm.

In order to live up to the harshest off-road conditions, the BMW G 450 X has a light, impact resistant and highly stable plastic bash plate fitted as standard and that has already proved itself in racing at the highest level, including the brutal Erzberg Enduro.

The motorcycle also has a double-butted Magura aluminium handlebar that guarantees optimum control on all rides.

Ground-breaking coaxial design provides ultimate traction.

The real finesse in the chassis and a unique feature of the G 450 X is the coaxial mount of the swing arm and counter shaft. The swing arm pivot has been mounted through the hollow gearbox output so that there is no longer any change in length of the chain on compression and rebound over the entire suspension travel.

The chain tension remains constant independent of the compression position; the pinion, chain and chain ring are subject to less wear than in conventional designs.

The coaxial design virtually eliminates the negative torque effect of conventional designs. This allows the suspension to be extremely reactive while under acceleration, which greatly improves traction capabilities especially on challenging hill-climbs, exiting corners and whenever the rider is having fun.

Thanks to the patented coaxial mounting of the swing arm and counter shaft plus a wheelbase ideal for competition, the swing arm is 30 mm longer, markedly improving traction. The rear wheel remains in contact with the ground in all situations for longer. Increased traction equals increased ability to accelerate or brake.

When the front sprocket has to be replaced, the swing arm must be removed; however, in comparison to conventional concepts, this is not a particularly time consuming task.

The standard rear sprocket has 48 teeth, and the front has 15 teeth, with 13 and 14-tooth sprockets bundled with the bike's parts kit.

The BMW G 450 X is finished in the BMW Motorrad "Racing White" colour scheme, with typically blue BMW accents.

The digital information cluster provides electronic readouts for speed, operating hours, odometer, two trip metres, two stopwatch functions, clock, lap timer, speed averaging function and a maximum speed warning. The display backlight colour can also be changed from red to yellow through a series of stages.

The handlebar can be adjusted through a number of different stages as well, as is normal BMW practice for reach and angle of tilt.