ENGLISH
47
Engine
640 LC4
Design
Liquid-cooled single cylinder 4-stroke engine with balancer shaft and electric starter
Displacement
625 ccm
Bore / Stroke
101 / 78 mm
Ratio
11.7 : 1
Fuel
unleaded premium gasoline with at least RON 95 (USA = Premium RON 91) (RON 80-94 for other ignition curve
Valve timing
4 valves over rocker arm and 1 overhead camshaft, camshaft drive through single chain
Camshaft
249/1
Valve diameter
Intake: 36 mm Exhaust: 32 mm
Valve clearence cold
0,15 mm Exhaust: 0,15 mm
Crank shaft bearing
2 cylinder roller bearing
Connecting rod bearing
needle bearing
Top end bearing
bronze bushing
Piston
forged aluminium alloy
Piston rings
1 compression ring, 1 taper face ring, 1 oil scraper ring
Engine lubrication
two Eaton-oilpumps
Engine oil
see bellow #
Engine oil quantity
appr. 2,1 liters including frame
Primary ratio
straight geared spur wheels 31 : 79 teeth
Clutch
multi disc clutch in oil bath, hydraulically operated
Transmission
5-speed claw shifted
Gear ratio
1st
14:35
2nd
15:24
3rd
18:21
4th
20:19
5th
22:18
Ignition system
contactless DC-CDI ignition with digital advanced system type KOKUSAN 4K5
Ignition timing
adjustment to max. 38° BTDC at 6000 rpm
Generator
12V 200W
Spark plug
NGK DCPR 8 E
Spark plug gap
0,9 mm
Cooling system
liquid cooled, permanent rotation of cooling liquid through mechanic driven water pump
Cooling liquid
1 liter, 40% antifreeze, 60% water, at least –25 ° C (–13 ° F)
Starting equipment
electric starter and kickstarter
#
TECHNICAL DATA – ENGINE 640 LC4, 640 LC4 Supermoto 2004
0°C
32°F
10W/50
5W/40
JASO T903 MA
TEMPERATURE
Engine oil
Only use fully synthetic engine oils that meet the
JASO MA quality requirements (see information on
the can).
KTM recommends Motorex Power Synt 4T in the
10W/50 viscosity (for temperatures over 0°C, 32°F)
or 5W/40 (for temperatures under 0°C, 32°F).
BASIC CARBURETOR SETTING
Type
BST40-266
Main jet
152,5
Needle jet
X-6 689
Idling jet
45
Jet needle
6G5
Needle clip pos. f. top
3. from top
Mixt. adj. screw open
2,25
640 LC4
640 LC4 Supermoto
