Make Model



2005 - 07


Four stroke, single cylinder, SOHC, 4 valves per cylinder


510.4 cc / 31.1 in
Bore x Stroke 95 x 72 mm
Cooling System Liquid cooled


Pressure circulation lubrication with two rotor pumps


Keihin MX FCR 3900E

Spark Plug



CDI Kokusan 4K-3


12V 8Ah, maintenance free


Electric & kick


Wet, multi-disc


6 Speed

Primary Drive Ratio

33:76 Z

Gear Ratios

1st 14:34 / 2nd 17:31 / 3rd 19:28 / 4th 22:26 / 5th 24:23 / 6th 26:21

Final Drive Ratio


Final Drive



Central tube chrome-moly-steel frame

Front Suspension

WP 4860 MA usd fork

Front Wheel Travel

300 mm / 11.8 in

Rear Suspension

WP Progressive Damping System shock absorber, aluminium swing arm

Rear Wheel Travel

335 mm / 13.2 in

Front Brakes

Single 260 mm disc, floating caliper

Rear Brakes

Single 220 mm disc, floating caliper

Front Tyre

90/90 - 21

Rear Tyre

140/80 - 18
Steering Head Angle 63.5°
Wheelbase 1481 mm / 58.3 in
Ground Clearance 380 mm / 15.1 in
Seat Height 925 mm / 36.4 in

Dry Weight

113 kg / 249 lbs

Engine Oil Capacity

1.25 L / 1.32 US qt / 1.10 Imp qt, full synthetic oil (Motorex Power Synt 4T 10W/50)

Fuel Capacity

8.5 L / 2.2 US gal / 1.9 Imp gal

KTM has now been around as a manufacturer for fifty years but only in recent times has the company reached a position where it can take on the Japanese in the sales race.

The name KTM is derived from the names of the company founders, Ernst Kronreif and Hans Trunkenpolz, while the third letter represents the geographic location of the KTM factory, Mattighofen in Austria.

After some troubled times during the 1980s, where the KTM name was damaged by build quality problems, the company reinvented itself in 1992 and started a long road to recovery.

A new high-tech production line was brought on line in 1999. This new facility brought about superior levels of quality control and set the groundwork for the sales success that KTM now enjoys.

KTM has also been recording an incredible level of racetrack success around the world, including many recent world championship wins. In Australia Craig Anderson piloted his KTM to a major trifecta this year by wrapping up the 2002 Australian Supercross, Motocross and ThumperNats Championships.

The 2003 KTM model range recently landed in Australia. Recently I was lucky enough to sample the range-topping 525 EXC and took the opportunity to explore the fantastic trails in the BlackWood River Valley surrounding the towns of Balingup and Nannup.

As soon as I hopped aboard the KTM I was under no illusion that I was on a race ready machine. High quality Magura bars are set in a high and aggressive position, helping the rider to correctly weight the front wheel when entering a turn. A long and slim black seat makes it easy for the rider to get forward, or alternatively slide back to improve traction.

And traction is something that is easily broken when you let the 510.4cc four-stroke single have it’s head. I couldn’t imagine needing more grunt than the KTM provides. Massive bottom-end urge is available just off idle and proves very tractable and secure when negotiating tricky terrain. The power then gently builds in to a strong mid-range before coming on hard with an addictive top-end hit. Even more impressive is the fact that the liquid-cooled engine is quite smooth running for such a large capacity single.

A 39mm Keihin MX FCR carburettor delivers the fuel to the formidable engine from a small 8.5 litre tank. Carburation is excellent with the KTM never threatening a hiccup, smooth throttle response was available in any situation. Something that is definitely required with the amount of urge available. The throttle has quite a long travel, which also aids control; a quick action throttle would not be welcome on the 525. The machine starts easily from cold with the choke on and a quick press of the electric start button. The choke is well hidden though and requires some contortion of the fingers to turn on or off.

Shifting gears is no chore thanks to an incredibly smooth six-speed gearbox. Not only are clutchless upshifts remarkably smooth, but the clutch can also be negated on downshifts in certain situations. The more race focused SX model makes do with only four gears.

White Power supplies the suspension components, not surprising as KTM acquired WP in 1995. USD 48mm forks are standard across the whole EXC range, up in size from the 43mm items fitted in 2002.

KTM - "In contrast to the 2002 fork, the new fork now has three bushes per fork tube, which ensures a better guidance of the inner tubes during compression travel. Both wipe and radial shaft seal, as well as the bearings, were obtained from new suppliers and, in combination with a new fork oil, ensure a markedly improved response. KTM also improved the chromium quality of the fork coating to prevent excessive “pumping up“ of the fork in use."

The adjustable rear shock has also been upgraded for 2003. Neither end caused me any problems during my time with the machine but I think the more hard-core dirt rider will maybe want to firm up both ends a little.

KTM's comments on the shock changes from 2002 to 2003 - "A bigger compensating tank and a larger oil volume prevent premature fading. Changed flow cross-sections for the oil stream and new tuning setups provide better progression. This results in an improved response with a greater impact resistance."

Gone is the clear tank of the previous EXC models, the orange coloured SX tank is now standard across the EXC range. This point has not been universally well received as the previous clear tank made it easy to see how much fuel was remaining in the tank. And with only 8.5 Litres of capacity, fuel range always has to be on your mind if going adventuring. Replacing the standard tank with the 13.5 litre cell from the MXC model may be a popular option for the trail rider.

Brembo supply the brake components which clamp on slotted, wave rotors, 260mm at the front and 220mm at the rear. Both brakes work very well, but could not be called exceptional in their performance. The levers are high quality items and adjustable for reach.

A digital speedometer with optional trip master controls aids navigation. Strangely the dash illuminates whenever the machine is rolled, even when the engine is not running. It is wired directly to the battery, as the machine has no ignition key, just a start and stop button. Thankfully a frame-mounted steering lock is provided but in 2003 I think we should get a bit more physical security than this. But that said, Honda’s XR models and Yamaha’s WR machines offer only the same, or even less, security than that found on the KTM. It is not surprising that recent statistics indicate that roughly one out of every 25 registered dirtbikes will get stolen. Those figures do not even include the statistics for machines that are never road-registered; if those machines were included one could expect that 1:25 ratio to get considerably worse.

In my opinion the KTM is more suited for the experienced pilot than the casual trail rider. It also more physically demanding to ride than some of the softer opposition which adds perhaps even more pertinence to my previous point in regards to rider experience.

I should also point out that this review was undertaken from the average trail riders point of view. It was certainly not a hard-core track test with really hard berm hits or big jumps. The KTM may be capable of leaping tall buildings in a single bound, but this test rider is not. This review is done from a casual trail riders perspective.

The 2003 KTM 525 EXC retails for $12,485 plus on road costs. KTM back the machine with a three-month warranty covering parts only. This is perhaps a little stingy, but Yamaha do only offer the same coverage on their WR models. In contrast Suzuki, Kawasaki and Honda cover their 400cc models with a full 12-month parts and labour warranty. But those machines can’t match the outright performance and race readiness offered by the KTM or Yamaha machines.

In recent years the trail rider has been spoiled for choice with various size machines on offer from nearly all manufacturers. One thing is for certain, the KTM is definitely at the more serious end of the scale when it comes to dirt ability. The KTM also offers perhaps the best dirtbike engine yet produced, with masses of grunt available in any gear, at any revs, the 525 EXC is not a machine for the feint hearted.