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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