There are times in your life when you just have to kick yourself and make sure the happenings surrounding you are a reality, and last week I had more than a few of those at the Australian launch of KTM’s EXC off-road range.

With the entire range of the Austrian manufacturer’s class-leading EXCs on hand to sample for two epic days of riding, our ride was made that much better under the guidance of West Coast Trailbike Safaris in the south west of Western Australia.

Heading into the launch I wasn’t quite sure what to expect with fellow riders ‘warning’ me of slick pea gravel and spongy sand, and as a rider who usually rides either road bikes or motocross, the unknown of an off-road adventure was exciting in its own way.

I’d previously travelled to Spain for the launch of the 2008 model EXCs and had an excellent time on a set course, but the opportunity to stretch our legs and take part in a real tour of the WA while testing the bikes was almost too good to be true this time around.

A mix of sloping hills on green countryside was soon followed by tighter riding sections in the pines, with a mix of those pesky dirt roads that consist of major amounts of pea gravel to keep you on your toes.

Deep water crossings and steep, rocky, hills were also on the menu for the journey, with the odd tree-crossing and a top secret sand dune ride at dusk proving a mighty popular finish to day one.

But while the tour from operator John Staines and wife Georgina was as good as it gets in the world of enduro riding, the real reason we were there was for the KTMs, and it’s safe to say that the best just got even better.

It may be a big call to label a particular manufacturer the best in the discipline, but if you were to judge it over the entire range then the eight EXC models that KTM brings to the battle offer an extremely wide variety of bikes with just about something for everybody.

For this week we’ll start by reviewing the four-stroke range, featuring the 250 EXC-F, 400 EXC, 450 EXC and 530 EXC, while next week we’ll bring you part two of the Launch Test with the two-stroke 125 EXC, 200 EXC, 250 EXC and 300 EXC.

When it comes to the 250cc four-stroke class there aren’t a massive amount of bikes in the ranks, but the ones that are in it form the platform of a mighty competitive category where every inch of usable horsepower counts.

KTM has essentially focussed on improving reliability in its 250 EXC-F for this year, with an optimised decompressor design also assisting in the bike’s starting abilities.

The chassis has received a host of upgraded components, including revised suspension re-valving that includes a needle design in the PDS at the rear, which is similar to that found on the SX model from the 2009 range, albeit with an enduro setting.

Other component changes on the 250, all of which are also featured on the remainder of the models including the aforementioned suspension changes, are a more compact and lighter Brembo master-cylinder and caliper, new TOYO front brake pads, an optimised airbox, a new air filter, 100g lighter Excel rims, a DID X-ring chain, a 1.8 bar radiator cap (instead of 1.4), and Renthal Diamond grips.

On the trails the 250 EXC-F is clearly agile and makes riding through the tighter sections incredibly easy, with the light weight and handling of the bike making it instantly comfortable.

What is so good about the 250F is that it has a solid load of torque to help you get up some of the more technical climbs or through the deeper water crossings, but you don’t get fatigued on it as quickly as you do on some of the higher capacity bikes.

You can place the bike where you want, it won’t bite back too hard if you make any major mistakes, and it’s awesome fun when you’re looking to get into it and open up the throttle to really hear the bike rev.

An added feature of the 400, 450 and 530 EXCs is that they all have a new frame design that has the steering head 10mm lower than in 2009, which lowers the seating and fuel tank position with an optimised feel of the front-end according to KTM’s press documents.

All of KTM’s bikes feel race-orientated and have a riding position that invites aggressive riding, but whether you’re going fast or cruising, they all have a top ergonomics package that feels narrow in between your legs while maintaining stability at speed.

Despite the steering head being lower and slightly lowering the seat height, all of the models are still quite tall from the ground, but the relationship between the footrests and seat is comfortable for a variety of riders.

At a claimed weight of 105.7kg dry the 250F is by far the lightest of the bunch as mentioned earlier, while the 400, 450 and 530 all weigh in at 113.9kg – a noticeable difference, while still retaining much of the rideability that the 250 features.

Admittedly I didn’t get the chance to test the 2009 model EXCs and the ride in Spain on the 2008 models is a distant memory at this point, but KTM’s claims of a better weight balance and greater control over the front wheel on the 400, 450 and 530 seem to have hit the design brief, because over two days of around 430 kilometres in a variety on terrain and conditions, I never did experience any real close calls while cornering (making my way through the water crossings and up the hills was a different story!).

Even the big-bore bikes were more agile and easier to ride than expected in the tighter confines in both sand, mud and on harder surfaces, while all three shined when on the transport stages of dirt roads in between trails.

Braking with the revised master-cylinder and caliper offers a great feel of the front lever as it’s not touchy at all and easily adjustable, and the brake pads have superb stopping power without being too aggressive.

Needless to say, while speaking of the hand controls, the clutch is super light on each of the models from the 250 to the 530 and all in between, further assisting in limiting fatigue over the long haul.

One place you certainly can’t go wrong on the 400, 450 or 530 is on the climbs, because you basically just have to steer it in the direction you want to go and lag it up there in your selected gear – or you can hit it with pure aggression as photographer Adam Riemann did on a massive climb that goes by the name of ‘Bertha’.

Not only are the large capacity engines good for climbing, but sand riding (especially in the dunes), muddy sections, and water bog holes are almost a cinch with the high power output on each of the bikes equalled by ultra-smooth throttle responses.

The engine on the 450 remains  almost identical to last year’s bike apart from an optimised decompressor spring for easier starting and a reinforced gearbox (1,2,5,6 idler gears) for durability purposes.

Its smaller sibling 400 also had the reinforced gearbox, and both have a reworked chain adjuster and clamping rail for a safer tensioning of the timing chain and also for noise reduction.

On paper you’d think that there would be minimal differences between the 400 and 450, but out in the bush there are massive differences, with the 400 offering such a usable range of power that’s spread through a wide selection of gears.

For me, I actually prefer the slightly softer power of the 400 that permits a little more aggression, but in saying that, the 450 is surprisingly easy to throw around and control in its own completely different way to the 400.

In fact, if I had the best of both worlds, I’d start the day on the 450 while my energy levels were high and then drop down to the 400 in the afternoon as the lazy mistakes start creeping in.

Both sap energy quicker than the 250, while the 530 is on the other end of the spectrum with big power and torque figures that can really get a hold of you if you don’t give it the respect it very rightly deserves.

As a rider who usually rides 250Fs in motocross with the odd 450 outing, I was a little nervous when handed the reins of the 530, but I was relieved to recognise almost straight away that it’s a friendly thumper that is developed to make tractable power at all times.

This is probably thanks to the new camshaft timing that has been designed for smoother power, while a revised ignition timing offers better combustion and performance overall.

Like the 400 and 450, the 530 also features the reinforced gearbox, reworked chain adjuster and clamping rail.

Tall gearing on all of the bikes contributes to the smooth powerband they all feature, and it’s the specifically placed gear ratios that enable the bikes to perform at their best whether you’re taking on technical single track or blasting down some fire road sections.

The most rewarding thing about a launch with KTM, two-strokes included, is that you can step from one bike to another and feel comfortable immediately, with a consistent range of bikes that are purpose built for the differing environment that enduro riding often surprises us with around each bend.

Capping off the orange army are brilliant touches such as graphics that are embedded within the radiator shrouds, while this year’s models also come with awesome race-style graphic stickers for the front and rear fenders.

Other touches such as features like the accessible airbox (you can get into the airfilter without a tool in sight) make the bikes easy to work on if you’ve been slogging about in dusty conditions and need a quick change, while standard hand guards do wonders when putting in a long ride.

Quality is something that KTM is known for in its European nature, and for 2010, that quality will be sure to boost the EXC range well up the order in both group tests and the sales charts.

Check back next Friday for a full review of the two-stroke range.

Click here for detailed changes in the entire 2010 KTM off-road range

Click here for our image gallery of the new models

Note: Specification sidebar is still to come for all models.