Yamaha XT 660X

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.

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.

Review

Yamaha's new supermoto streetbike

After riding just one block through a grid-locked inner Sydney heading for that Australian icon the Harbor Bridge, the light bulb went on in my brain. This was the type of bike that most motorcyclists should own, a bike for all seasons and all reasons.

But as I edged past yet another hyper-sportsbike, its rider hunched painfully over clip-on handlebars, I realized the enormity ahead for Yamaha's sales staff. In countries where big, powerful, twin- and four-cylinder engines have ruled since the early 1970s, such as Australia and America, what will it take to wean them?

I glanced across at my riding companions on this world launch. The European journalists already know all about the benefits of single-cylinder dirt-bikes with road wheels and brakes. Supermotard-style motorcycles are riding a surge of popularity on the other side of the world but Yamaha is taking a bit of gamble in other markets.

The XT660X goes on sale in Australia within a few months. If it can be priced around $A10,000 it has a fighting chance against middleweight naked bikes. This supermoto bike will be followed by an enduro version, the XT660R.

Where the XT stands out is its versatility and ease of use. The launch route reminded me of riding in California's San Gabriel Mountains and the coastal Highway 1. It wound from the Rocks in busy central Sydney, up freeways to dirt trails alongside the Hawkesbury River, and then some canyon carving on paved backroads. It's as much fun as you'll have on a bike and all within the legal speed limits of 35 mph in built-up areas, 70 mph on freeways and 65mph on country roads.

2004 Yamaha XT600X - Motard
On the international launch, which was combined with the R1, quite a few of the journalists quietly admitted they'd had as much fun with the supermotard as the powerhouse sports king. Yamaha's XT series has been around since 1976, and alloy-tank versions from the late 1970s are achieving classic status. This big, air-cooled single became a do-it-all enduro. It won the first Paris-Dakar rally before the Tènèrè became an early favorite for round-the-world travelers.

For 2004, the XT660 has been completely redesigned. Only its engine capacity is carried over from the faithful old Tènèrè. Now liquid-cooled, the single-cylinder has a 100mm bore and 84mm stroke. The 10:1-compression forged piston runs in a ceramic-composite plated bore. A fuel injection system with a 44mm throttle body feeds a new SOHC, four-valve cylinder-head (with larger inlet valves). Twin big-bore exhausts let the engine breathe while meeting pollution regulations.

Power delivery is crisp, with a flat torque delivery that encourages aggressive acceleration out of tight corners. You can get all the power to the ground. The bike handles all types of road surfaces and doesn't feel out of place battling semi-trailers and buses on the freeway with little buffeting from other traffic.

On back country roads it can be pushed aggressively into corners and leaned as far over as any big-bore sportsbike. I even touched down a footpeg, which isn't bad considering the high posture of a dirt-derived bike.

Considering its origins, the X supermotard doesn't feel like a compromise created from its dirt sibling. I know, because I have previously ridden a Honda XR turned into a supermotard. It ran road wheels and brakes but retained its too-supple off-road suspension. Its power delivery was a bit breathless and flat, as well.

I also own a KTM Duke II, which has excellent WP suspension and a snappy engine with lots of top-end zing. Unlike my vibrating Duke II, the XT 660X is the sort of bike you could ride every day while you had your dream bike (whether it be cruiser, tourer or sportsbike) sitting in the garage for those special days.

2004 Yamaha XT600R - Motard
The XT feels unbreakable and undemanding to ride while European-inspired styling gives it a road presence. But you really have to ride one to understand what I'm talking about.

On paper, this factory supermotard doesn't measure up. It weighs as much as Yamaha's R1 with less than a third of the power. A seemingly weedy 48-hp Single pulling 381 lbs. (dry weight) of motorcycle around is never going to set the world on fire. But the XT660X sparks enthusiasm after just a few minutes in the saddle. It's all to do with the fun factor and being able to ride at full throttle anywhere.

Whereas a lot of lightweight dirt bikes feel skittish and oversprung for the road, the XT physically feels more like a 600cc naked. Its weight means it isn't knocked around by wind blast and the seating position works well, giving good handlebar leverage while positioning the feet in a more sporting stance.

Power is delivered in a way that plants the rear wheel in the tarmac from very low revs while accelerating much more crisply than a traditional big-bore enduro. It doesn't have the top-end rush of KTM's exhilarating 640 single but it also doesn't have the tiring vibration, either.

The tubular steel frame, with two upper frame tubes, uses the engine as a stressed member to result in a chassis claimed to be 60% stiffer than its predecessor. While both road and dirt models have a 43mm front fork, the X version is more road-oriented. The 17-inch spoked Excel road wheels run sticky 120/70 front and 160/60 rear radial tires. The 320mm floating disc fills the front wheel and is as good as it looks, being fitted with a Brembo four-piston caliper.

2004 Yamaha XT600R - Motard
The narrower and tighter the roads get, the better the XT660 works. This means it is a cinch to ride through busy city streets and serious fun on empty, winding backroads. Fitted with sports-spec road tires designed for much more powerful motorcycles begs for an aggressive cornering style. Throw it at a corner and keep the throttle on like you would in the dirt and it steers quickly. The suspension soaks up bumps without throwing the bike off-line. It doesn't dive excessively under brakes and there isn't the wash-out-type feeling you sometimes get from dirtbikes ridden hard on the road. The XT660 holds its line with no wallowing.

It's a totally different sensation to riding a middleweight naked hard, but a lot of this is because of the unnecessarily tall seat height. The secret is to keep the throttle pinned and push your weight over the handlebars. If you think you're overcommitted to a corner, back off a touch then reapply the throttle and crank the bike right over. It can take it.

The suspension has been well tuned for this application. It isn't just a dirtbike with road wheels slapped on, it's a total package. In the right hands, the XT660X would surprise a lot of hypersports riders in a canyon chase, which is pretty high praise for such a humble machine.

With all the fun of a dirtbike but with road-tuned suspension, wheels and brakes, the XT660 is the everyman's supermotard. It isn't a lightweight, race-souped single that's a bear to live with in the suburbs. You could ride it to work every day, then thrash it up secondary roads and fire-trails at the weekend.

If it's sold at the right price, it could be a great runabout for the motorcyclist who already owns his dream bike. It could also be cheap fun for anyone who loves two wheels. The XT660X doesn't break new ground with technology but it takes motorcycling into an entirely undeveloped area, that of the supermotard.

2004 Yamaha XT600R - Motard
But motorcyclists are a conservative lot, whether it be the cruiser scene or the clip-on clique. Change comes slowly. If Yamaha recoups development costs with healthy sales in Europe, then maybe the XT660X will be released in new markets at a rock bottom price.

Unfortunately for American supermoto fans, there are currently no plans to import the XT to the U.S.

"There isn't enough support from dealers or customers to bring a bike like this to the US.," says Yamaha spokesman Brad Banister. "There will certainly always be a few vocal motorcyclists who must have the bike, but we haven't heard resounding interest in this type of motorcycle like we have with, say, the FJR1300, which was originally a Europe-only model."

This position by Yamaha is a bit of a surprise considering its support and enthusiasm for supermoto racing.

"We certainly love all forms of motorcycle competition, however a serious supermoto race bike and streetbike would be mutually exclusive," Banister continues. "Serious racers will probably always convert competition motorcycles to supermoto specification rather than the other way around. Yamaha has been very good about studying the market and determining what products make sense for the market place. As it stands right now, the market won't support this type of product in any significant quantities."

Source Motorcycle_USA