2005–2006 · Supermoto · Buyer's Guide
Raw Thumper, Razor Handling
The 640 LC4 Supermoto is KTM's supermoto idea in its rawest street form. A liquid-cooled 625 cc single makes 54 hp at 7,000 rpm and 41 lb-ft at 5,500 rpm, and sends it through a 5-speed box and a chain. The engine hangs in a steel trellis frame. It has an upside-down fork up front and a shock out back, with 10.8 in (275 mm) of travel at both ends, and it rolls on 17-inch street rubber, a 120/70 front and a 160/60 rear. There is no ABS, no traction control and there are no ride modes. What you get is a narrow, off-road-bred chassis dressed for asphalt and a thumper that pulls hardest in the midrange, which is where a supermoto spends its life.
On the road it changes direction with almost no input, and the lean clearance is effectively unlimited for street riding. It suits a rider who wants short, hard rides on tight back roads and treats city traffic as a playground. The caveats are real. The seat is 35.8 in (910 mm) high, the 2.5 gal (9.5 L) tank keeps range short and top speed is 99 mph (160 km/h). As these bikes age, keep an eye on the top cam bearings, the voltage regulator and stator, the water pump seal, the starter motor, the clutch slave cylinder and the rocker cover gasket. Buy one with a documented service history.
Spec sheets don't ride bikes, but they set the baseline.
| Power | 54 hp (40 kW) @ 7,000 rpm |
|---|---|
| Torque | 41 lb-ft (55 Nm) @ 5,500 rpm |
| Displacement | 625 cc |
| Engine | Single-cylinder |
| Cooling | Liquid-cooled |
| Gearbox | 5-speed |
| Final drive | Chain |
| Fork | Upside-down (USD) |
| Front tire | 120/70-17 |
| Rear tire | 160/60-17 |
| Ground clearance | 11.0 in (279 mm) |
| Front travel | 10.8 in (275 mm) |
| Rear travel | 11.8 in (300 mm) |
| Seat height | 35.8 in (910 mm) |
| Fuel capacity | 2.5 gal (9.5 L) |
| Top speed | 99 mph (160 km/h) |
Equipment check
Chassis
Cam bearing wear
Premature wear of the top cam bearings can cause noisy operation and potential engine damage.
Electrical gremlins
Voltage regulator and stator failures can leave you stranded; wiring can be temperamental.
Potential water pump seal failure
Some owners report coolant weeping from the water pump seal, which can lead to coolant loss if not addressed.
Starter motor failure
The starter motor may fail, often due to overheating or burnout, leading to difficulty starting the engine. Replacing the unit resolves the problem.
Clutch slave cylinder leak
The clutch slave cylinder may develop leaks when the engine is hot, causing clutch fluid loss and eventual clutch disengagement issues. Upgraded aftermarket units are a common fix.
Oil leaks from rocker cover
The rocker cover gasket may leak oil, especially after sustained high-RPM riding.
Where this KTM 640 LC4 Supermoto pulls ahead of — or falls behind — its rivals on the numbers, and the typical bike in its class on character.
Power
Torque
Displacement
Top speed
Seat height
Forget spec-sheet bragging. Here's who the 640 LC4 Supermoto is actually built for.
On the tight, slow sections of the canyons this thing is a riot, and it makes light work of LA traffic on the way out. On the fast sweepers, 54 hp and a 99 mph top speed leave you wanting more. Pick your roads.
Made for Angeles Crest Highway · Coronado Trail / US 191 · Highway 1 / Big Sur
Short, tight, technical corners are exactly what this bike was built for. The catch is getting there: a long highway haul from Atlanta or Knoxville on a buzzy single with a small tank is work.
Made for Tail of the Dragon · Back of the Dragon · Blue Ridge Parkway
It makes the twisty stretches a blast and looks right parked outside the BBQ joint. On a weekend loop with long straights between the good roads, the small tank and the vibration wear thin.
Made for Austin / Texas Hill Country · Texas Hill Country BDR-X · Twisted Sisters
If this one isn't quite the fit, these are the bikes worth riding back-to-back against it.
Successor · 2008–2009
The Urban Knife Fighter
Successor · 2005–2006
Dirt DNA, Asphalt Ready
Competitor · 2005–2010
Built for Pavement From Day One
Competitor · 2005–2007
Honda's Fun Lightweight Flickable Thumper
Same Platform · 2003–2006
Kickstart-Only Track Weapon