News 1 Jan 2009

Full Test: 2008 KTM EXC range

Moto Online travels to Spain to find out if KTM's '08 four-stroke EXC models in the orange army live up to expectations.

TECHNICAL FEATURES:

Features and styling

KTM’s goal of keeping its entire range of enduro EXC models looking and feeling very similar to each other has definitely become a reality. From the 250 EXC-F to the 530 EXC-R, these three models all look and behave basically the same apart from the obvious engine differences.

In 2007 the SX motocross range received a major overhaul and looked completely different than in previous years. That same look has been applied to the EXC enduro range this time around, and the lights and usual enduro parts help pull the look off even better than the motocross models.

The side shrouds and complete plastics are much more minimal compared with the 2007 models, and they are designed to be light weight. The radiator shrouds feature holes to allow air into the airbox after it flows underneath the seat.

The front ends of the new EXCs look tough, with a single triangular-shaped headlight giving the KTMs a distinctive new ‘face’. The lens is made of anti-scratch polycarbonate, and is light weight like most parts on the bikes.

The rear end has a mudguard similar to that on the motocross bikes, although it has an LED taillight attached. There’s also a numberplate support with indicators that is designed to be taken off easily for racing purposes.

The fuel tanks on the new EXCs all have excellent knee grip thanks to the holes that double as airbox intake holes, and all models have their own specific fuel capacities (9.2 litres for 250 EXC-F and 9 litres 450 and 530 EXC-R models). A new fuel cap also requires the rider to push a button to get it to rotate, putting an end to the leaky caps of old.

A new sidestand made of tapered aluminium is slightly longer than the ’07 model, and is now fitted directly to the frame instead of being braced by a link. It also features a larger plastic foot to improve stability when parked in tricky places.

The wheels have EXCEL rims with machined hubs and thinner walls, and lighter spokes give minimal unsprung masses.

All this makes the new EXCs vastly different to the previous models, and give them a completely different look and feel.

Engine

The all new XC4 engine on the 450 and 530 EXC-R models is the highlight for the four-stroke range this year, as it is completely redesigned exclusively for enduro riding.

The XC4’s state of the art design has both electric and kick starters, along with a six speed gearbox — all similar to last year’s model.

That’s about where the similarities end, and the XC4 has been designed lighter, with better power delivery and improved reliability. Both the 450 and 530 are similar in each and every way, apart from the displacement and gearing.

The 450 is a 449.3cc engine with a 95/63.4mm bore and stroke, while the 530 has a higher power output thanks to a 510.4cc engine. Its bore and stroke is 95/72mm.

Both engines have totally new cylinder heads, with one single overhead cam and four valves in each. The valve diameters have been increased, the intake valves are made of titanium and the valve angles have been decreased for a compact combustion chamber.

They also have weight-reduced rocker arms with shims, and the cam also serves as centrifuge for engine ventilation. A slanted head cover also makes valve access easier that previous models.

But what does all that technical info mean? Basically, it means the power is more ideal for enduro riding, while the reliability is better and it will be easier to maintain.

Vibrations have been decreased even more so than the 2007 model, as a rigid crankshaft operates a weight-optimised forged piston via a short con rod. This also increases reliability over the old model.

The counter balancer shaft in the XC4 engine, which is powered by the crankshaft, features laterally fitted balancer weights rotating outside the crank case and this also helps reduce vibration and gives minimal friction because the rotating weights are external.

There are now two separate lubrication circuits for the combustion tract and transmission/clutch to allow even more lubrication to the engine. There are also now three pumps — two pressure pumps, one suction pump — and only one oil filter.

The Keihin FCR-MX 39mm carburettor with acceleration pump and throttle position sensor stays, as KTM says it gives better throttle response at 39mm than bigger versions found on other brands.

Overall, the new XC4 engine is around half a kilo lighter than last year’s, although it is the most reliable and best performing ever from KTM.

The 250 EXC-F remains much the same as last year’s four valve, double overhead cam RC4 engine, which is based off of the 250 SX-F motocross model’s engine, but has changes to tame it down to suit enduro riding.

The only major changes for 2008 are that the valve train’s exhaust camshaft has new timing and optimised valve springs to make it more responsive and have a better power delivery. It’s also designed to be more reliable. The other change is a new ignition curve mapping — changed to help the bike perform better at low rpm.

All of the four-strokes share the same updated exhaust silencer, that feature catalytic converters to meet Euro III standards, while they also are shaped to suit the bikes’ overall new design.

Chassis

The frame used on the 2008 model EXCs has also copped a major redesign, with all bikes inheriting a new chromoly frame with massive oval lateral tubes. The frame is based off of the motocross range of last year with minor changes, and it is designed to produce optimal flex at the lowest possible weight. The sub-frame is made of rigid aluminium profiles.

The cooling system is now integrated in the frame’s triangle at the front of the bike, meaning less tubes and better cooling than last year.

The cast aluminium swingarm is laid out according to bending stress. It now flexes more for improved comfort, while a different mounting point for the WP PDS shock absorber gives a lot better, and more progressive, feel in the rear.

The shock absorber is now more adjustable with both high and low speed damping adjustments, and has 10mm more stroke than last year due to its mounting point on the swingarm. That also means that the piston speed is higher. The shock body is now made of aluminium. It has a wider range for setting up to suit each rider, and gives a smoother ride.

48mm upside down WP forks are used and are fully adjustable, with an additional preload adjuster for 2008. They feature a new setting, again to help make the riding comfort better, and just like the shock, they have a wider range of settings.

New fork protectors also wrap around further and help to stop rocks and other objects damaging the fork tube.

With all bikes sharing very similar frames and components, KTM has found a base to work from and has made it work extremely well.

I’ve almost completed a lap of the eight kilometre loop amongst the Spanish forest that has been mapped out by KTM’s test riders. My adrenalin is flowing, heart pumping, and I’m beginning to really get the hang of this enduro stuff. I carve through a tight left-hand turn and find myself splashing through a deep river before I know it.

No worries there; what’s a bit of water hurt anyway? I carry on, and soon enough I find myself on the bank of another river crossing. This one is much bigger. I do a double-take, before deciding to click into gear, stand up, and gingerly ride on through.

Rubber tyres on slippery wet rocks under water don’t mesh well, but I make it through before eventually coming to the end of the loop — with soaking wet riding gear and boots to prove my experience as the first rider through.

The trails I’m riding, about 150 kilometres north-west of Barcelona, are completely different than what I have ever ridden in Australia and give a real experience as I sample the latest and greatest 2008 model KTM EXC off-road enduro range.

A 40 hour trip from Sydney (thanks to delayed fights and lost baggage) was a gruelling experience, but as soon as I laid eyes on the new EXCs I knew it would all be worthwhile.

They look sleek, sharp, and fast — very much similar to last year’s KTM SX motocross range. The plastics are minimal, especially at the rear end of the bikes, and the EXCs different to last year’s models from front to rear. The plastics are also lightweight and feature integrated stickers on the radiator shrouds for minimal wear.

KTM has always produced excellent enduro bikes, designed specifically for off-road use and trail riding, but the redesigned 2008 models have been eagerly anticipated since spy photos surfaced late in 2007.

The KTM 250 EXC-F

The KTM 250 EXC-F

Leading the way for the Austrian company in Australian sales will be the ultra popular four-stroke range, consisting of the 250 EXC-F, 450 EXC-R and the big-bore 530 EXC-R.

All three bikes are surprisingly quite similar from a technical aspect, although the engines produce three vastly different weapons when blasting around the trails. The entire EXC range is based off of the successful SX motocross range, although minor changes are sprinkled throughout to make them more rideable in the tight confines of riding in the bush.

After spending almost two days in transit, I just couldn’t wait to get out in the open air and rip up some Spanish soil. The loop that we are riding features a massive variety of terrain including the aforementioned water crossings, tight single trails, and fire roads. Some of the downhills on the loop are frighteningly steep, while the uphill climbs get increasingly more difficult as we rip up rocks and chew the dirt.

I was particularly excited to climb aboard the new 450 EXC-R. The 450 class features the key players with over 10 manufacturers in the class, meaning KTM would have to really produce something special to outshine the rest.

It is my first bike I climb aboard while in Spain, and straight away it is impressive. Its comfort is typical KTM — very compact with excellent quality components. The feel isn’t a whole heap different to last year’s model, but they were renowned as the best in the business comfort-wise, so that’s actually a good thing. The hydraulically operated clutch can be pulled with one finger (as with all KTMs), and the gears shift seamlessly.

The mapped out loop begins a little easy with quite open areas and plenty of fire trail, and this really allows me to open up the engine and sample the power of the new XC4 engine.

I immediately feel the extra zap off the bottom, and the engine feels a little bit livelier than the former model. The engine features a host of changes (see engine breakout), and it gives the KTM some extra personality in the bush. The SX (motocross) models have always been known for their power, while the EXC enduro bikes are always much tamer and more friendly.

The new 450 has more aggressive power throughout the rev range, but it still does have the smoothness that KTM is known for when riding in the bush.

When really accelerating hard down the fire roads, it is the mid-range that is impressive as I bounce over rocks and fight through the dusty conditions. It keeps pulling along as I get one of few opportunities to open it right up and unleash the power.

I soon come into a tighter section of the trail that requires me to concentrate more and ride a little more precisely. It idles capably and is really easy to ride when I’m in between the narrow trees. I never need to worry about any stalling or any of the like, and that really stands out when I need to ride at crawling speeds in squeezy bits or downhills.

The KTM 450 EXC-R

The KTM 450 EXC-R

The Brembo brakes also work a treat down the hills, as the 260mm front disc offers good feel and stopping power. The rear has a 220mm disc that doesn’t give quite as much feel, but still does the job. The brakes are the same on all models.

Uphills are quite easy to do also, as the XC4 engine trots along, and first gear is actually quite tall. This allows me to use it in the difficult sections and not worry about stalling, while second is a good option for when things open slightly. I never did get to use sixth on any section of the track as it was all rather tight.

While the new engine is impressive and gives a little more excitement to the 450 EXC-R’s ride, KTM has not forgotten about the handling aspects of the new model. The newly designed frame is designed to flex, while being the lowest possible weight, and this makes it lighter and easier to steer than last year’s model.

It handles well in both tight and open stuff, although it is hard to compare the overall feeling compared with the terrain and places we ride here in Australia. The new bike doesn’t ever falter me though, and I find it easy to manoeuvre around trees and up and over steep hills and rocks. The light weight of the new model really helps me to last and not get too fatigued after quite a bit of time on the bike.

The front forks’ extra adjustability works well too, as adjustments to the forks proved effective and gave changes I could actually feel. They ride over bumps extremely well, although in some sections they could be softer for my weight (68kg) to allow the bike to tract better over logs, etc.

The shock absorber also has more adjustment for 2008, and provided a similar situation as what I felt from the front end. It wasn’t ever a huge problem and gave loads of feel that made the bike extremely rider friendly, although going a little softer in the spring rate would improve it that bit more.

After my experience on the 450, I was really looking forward to the big-bore 530 EXC-R. The 530 is actually very similar in all ways to the 450 apart from the XC4 engine’s displacement, and that is largely thanks to a higher stroke. The gearing is also slightly taller on the 530 to help woe the massive power. When you are sitting still, it feels much the same as the 450.

Once the engine is running and you take off, that all changes. Even though the chassis is much the same as the 450, I got tired quicker riding the 530. The extra power makes it much more difficult to handle through the tight stuff, but it was a whole lot of fun in the open sections of the trail.

There was also a ‘special test’ kind of track set up in a large open paddock area and that’s where the 530 was the most fun for me. I could use the power and click through the gears, without having to man handle it through tight obstacles. If the riding areas around you are pretty wide open, then the 530 is a pretty good choice.

It’s the best of the open class enduro machines on the market by far, although it just needs the correct riding areas to truly take advantage of its mighty horsepower. On the other hand, if you’re a big guy, you can take this beast anywhere and it will work well in both tight and wide open riding areas.

The KTM 530 EXC-R

The KTM 530 EXC-R

After wresting around the 530 for quite a while it was a huge relief to ride the 250 EXC-F as my final test bike of the day. I was feeling exhausted and the Spanish heat was getting to me, but the ease of riding the 250 revitalised me to have a good go again.

Again it feels strikingly similar to the other EXC models, but the light weight (it is claimed to be almost six kilograms lighter than the 450 and 530) really makes a huge difference as soon as I’m riding along the trail.

I feel more confident and aggressive on the trail, and I’ll admit, the smaller bikes suit my size and riding style. The weight of the bike allows me to place it where I want to on the trail, and the light weight makes it handle just that little bit better.

That isn’t always the case though, as sometimes at high speeds, the bigger and heavier bikes tend to be more stable thanks to their extra weight. In the tight enduro loop that we have to ride in Spain, the 250 is the choice for me — especially when I’m so tired from the heat and jetlag.

A 250cc engine is very user friendly, and this one is a bit more lively than last year’s — especially right off the bottom. It has that little bit more zap, although it still doesn’t have the punch of the Honda CRF250X enduro bike.

You can’t argue with the useability of the 250 EXC-F though, as KTM has kept the same smoothness that the older model was renowned for. It just has that bit more excitement now.

KTM knows how to make enduro bikes, and with a solid line up of EXCs for 2008, the Austrian company might just regain that overall dominance of off-road weapons that it enjoyed just a few short years ago. The orange army is complete and ready for battle.

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