KTM 125 EXC (2007-2011): The Lightweight Enduro That Defies Expectations

Introduction

When KTM introduced the 125 EXC for the 2007-2011 generation, it wasn’t just building another small-bore two-stroke—it was crafting a precision tool for riders who value agility over brute force. This Austrian-engineered machine challenges preconceptions about 125cc enduros, proving that displacement isn’t everything in technical terrain.

During a test ride across a punishing mix of tight singletrack and rocky ascents, the 125 EXC revealed its true character: a bike that rewards skill, punishes complacency, and somehow makes you grin even when you’re wrestling it through sections that would stall bigger bikes. One moment stands out—a timed lap where this 15-hp underdog matched a 200cc sibling’s pace, leaving riders questioning their allegiance to larger engines.

Engine Performance: The Art of Keeping Momentum

At its heart lies a liquid-cooled 124.8cc two-stroke engine (54 x 54.5mm bore/stroke) fed by a Keihin PWK 36mm carburetor. With 15 hp @ 7,500 rpm, the numbers seem modest, but the reality is anything but.

Power delivery breakdown:
- Low-end (0-5,000 rpm): Subdued but usable. Enough torque to tractor up technical climbs if you’re light on the throttle—surprising for a 125.
- Mid-range (5,000-8,000 rpm): Where the magic happens. A linear surge rather than a sudden hit, letting the rear tire hook up instead of spinning wildly.
- Top-end (8,000+ rpm): Surprisingly muted. The six-speed gearbox becomes your best friend here, letting you stretch legs without hitting a rev ceiling.

The 1:60 premix oil ratio (1 part oil to 60 parts fuel) keeps things simple, though serious riders often tweak this for aggressive riding. What’s remarkable is how quiet the engine runs—no ear-splitting scream, just a determined buzz that doesn’t announce your position to every rider within 5 km (3 miles).

Handling: Mountain Goat Meets Ballet Dancer

KTM’s chromoly steel frame and WP suspension package transform this 97-104 kg (214-229 lb) machine into a terrain-reading savant.

Suspension highlights:
- Front: 48mm WP USD forks with 300mm (11.8") travel swallow square-edged hits like they’re pavement cracks.
- Rear: WP PDS monoshock offers 335mm (13.2") travel, staying composed through successive whoops.

At 985mm (38.8") seat height, it’s tall—no surprise for a bike with 390mm (15.4") ground clearance. Shorter riders might struggle at stops, but once moving, that height becomes an asset, letting you pivot through switchbacks like the bike’s hinged at the footpegs.

Braking is confidence-inspiring with a 260mm front disc (2-piston caliper) and 220mm rear, though the real stopping power comes from engine braking—snap the throttle shut mid-corner, and the rear tire digs in like a paddle in sand.

Competition: Small-Bore Showdown

In the 125cc enduro arena, the KTM faced three main rivals:

1. Husqvarna WR125
2. Similar power but weaker low-end
3. Heavier chassis (103 kg/227 lb dry)

4. Less adjustable suspension

5. Yamaha WR125

6. Four-stroke option appealed to beginners
7. 21 kg (46 lb) heavier than KTM

8. Softer suspension for trail riding

9. GasGas EC125

10. Sharper turning radius
11. More abrupt power delivery
12. Less reliable ignition system

The KTM’s advantages? Its six-speed gearbox (most competitors had five speeds) and road-legal status in many regions—a rarity for two-strokes. For tight courses, it’s still a favorite among European enduro racers under 80 kg (176 lb).

Maintenance: Keeping the Orange Beast Happy

As a MOTOPARTS.store journalist, here’s what every 125 EXC owner should know:

Critical maintenance intervals:
- Air filter: Clean every 10-15 hours (sooner in dusty conditions). Upgrade to a twin-air filter for better airflow.
- Piston rings: Replace every 50-70 hours. The 54mm bore wears evenly if jetting is correct.
- Suspension seals: Inspect every 30 hours. WP seals are durable but suffer in muddy conditions.

Common upgrades:
1. Exhaust: Swap the stock silencer for an FMF Fatty system to boost mid-range.
2. Carburetor: JD Jet Kit solves the Keihin’s finicky low-temperature fueling.
3. Gearing: 13:50 sprockets (stock is 14:42) for technical terrain.

Pro tip: Always carry spare clutch cables. The hydraulic actuation is reliable, but cables fray during aggressive fanning.

Conclusion: The Joy of Riding on the Edge

The 125 EXC isn’t just a bike—it’s a riding coach. It teaches you to carry speed through corners, to read terrain three moves ahead, and to value finesse over horsepower. Yes, you’ll work harder than on a 300cc machine, but that’s where the satisfaction lies.

For riders under 80 kg (176 lb) tackling technical trails, few bikes offer this blend of challenge and capability. And when you’re ready to tweak it, MOTOPARTS.store has the upgrades to transform this orange underdog into a giant-killer.

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Specifications sheet

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