Supermoto is steadily gaining momentum around Australia. The opening round of the 2004 Australian Championship was played out last weekend.  A supermoto ride day is being staged at Cockburn Raceway this Sunday in WA. December 5 sees the opening round of the NSW Summer Supermoto Challenge at Oran Park

The bikes used for hard core competition are normally the latest lightweight and very powerful motocross machines modified with road sized rims and sticky rubber. While this makes for a great race package the high servicing requirements and little thought for rider comfort can make them a bit painful on the street, not only to the backside but also to your back pocket!

So for street duties it makes sense to have something in a slightly lower state of tune. With a few more cubes so the whole drivetrain is less stressed and can reliably cope with plenty of street kilometres. Yamaha have recognised this and produced a street based supermoto dubbed the XT660X.

Yamaha have produced liquid-cooled 660cc singles for some years in a variety of models.

In XT660X guise the compression is bumped up to 10.0:1 from the previous XTZ660s 9.2:1. Continuing with the performance theme the new bike benefits from a much changed cylinder head. The new 21% lighter cylinder head has been simplified somewhat with less moving parts but the rocker arms feature roller bearings for the first time on a Yamaha motorcycle. Mechanical losses easily rob power in a large single cylinder engine compared to multi-cylinder powerplants, this move has been part of the effort to reduce friction losses.

Strengthening and durability measures include a new anodised forged aluminium piston which slides in a ceramic composite plated cylinder. The previous XTZ model used a steel sleeve cylinder. The new much lighter bore provides better thermal transfer and reduces oil burning. Helping to reduce vibration is a larger balancer to offset the possible drawbacks likely with the move to a 1kg lighter crankshaft. The crankpin is 10% larger for better durability.

A fuel injection system draws its supply from a 15 litre tank while a pair of stainless steel mufflers expel the gases.

Power is transferred through a 15% larger clutch to a five speed gearbox.

A new diamond style frame offers decreased trail while a much stiffer swingarm helps cope with the side loadings able to be achieved with the fitment of the sticky Pirelli 160/60-17 rear hoop. Up front is a 120/70-17 tyre is suspended from large 43mm Paioli forks which benefit from cross bracing.

Brembo supply the four-piston aluminium caliper which clamps on a generous 320mm disc rotor. At the rear a single piston Brembo caliper grips a 245mm disc rotor.

An immobilizer system integrates with the multi-function instrumentation featuring an LCD speedometer along with the usual bank of idiot lights.

At $11499 the XT660X has plenty to offer for you to get started in supermoto.  At 173kg dry it will never be a dedicated race bike. But you can have plenty of fun without going racing, so if that is your bag then the XT660X would be a wise choice.

SPECS - Yamaha XT660X

• Engine: 660cc, Liquid-cooled 4-stroke 4-valve single

• Bore x Stroke: 100 x 84mm

• Compression: 10.0:1

• Induction: Fuel injection

• Starter: Electric

• Transmission: Five speed

• Final Drive: Chain

• Wheelbase: 1,490mm

• Dimensions (L x W x H): 2,175 X 860 X 1210mm

• Seat Height: 875mm

• Dry Weight: 173kg

• Fuel Capacity: 15 litres

• Tyres: Front _ 120/70-17; Rear _ 160/60-17

• Suspension: Front _ 43mm Paioli forks; Rear _ Kayaba single shock

• Brakes: Front _ 320mm single disc, Brembo four-piston caliper; Rear _ 245mm single disc, Brembo single piston caliper

• Price: $11499

• Warranty: Two years, unlimited kilometres