KTM 125 SX User Manual

21 TECHNICAL DATA 112
Sixth gear 22:24
Ignition Contactless controlled fully electronic ignition with digital igni-
tion adjustment, type Kokusan
Spark plug NGK BR9 ECMVX
Spark plug electrode gap 0.60 mm (0.0236 in)
Starting aid Kick starter
21.1.3 250 SX
Design 1-cylinder 2-stroke engine, water-cooled, with reed intake and
exhaust control
Displacement 249 cm³ (15.19 cu in)
Stroke 72 mm (2.83 in)
Bore 66.4 mm (2.614 in)
Exhaust valve - Beginning of adjustment 5,550 rpm
Exhaust valve - end of adjustment with red auxiliary spring 7,200 rpm
Exhaust valve - end of adjustment with yellow auxiliary spring 7,900 rpm
Exhaust valve - end of adjustment with green auxiliary spring 8,400 rpm
Crankshaft bearing 1 grooved ball bearing/1 roller bearing
Conrod bearing Needle bearing
Piston pin bearing Needle bearing
Pistons Aluminum cast
Piston rings 2 half keystone rings
X (upper edge of piston to upper edge of cylinder) 0… 0.10 mm (0… 0.0039 in)
Z (height of control flap) 48 mm (1.89 in)
Primary transmission 26:72
Clutch Multidisc clutch in oil bath/hydraulically activated
Gearbox 5-gear, claw shifted
Transmission ratio
First gear 14:28
Second gear 15:24
Third gear 18:24
Fourth gear 21:24
Fifth gear 22:21
Ignition Contactless controlled fully electronic ignition with digital igni-
tion adjustment, type Kokusan
Spark plug NGK BR 8 ECM
Spark plug electrode gap 0.60 mm (0.0236 in)
Starting aid Kick starter
21.1.4 250 XC
Design 1-cylinder 2-stroke engine, water-cooled, with reed intake and
exhaust control
Displacement 249 cm³ (15.19 cu in)
Stroke 72 mm (2.83 in)
Bore 66.4 mm (2.614 in)
Exhaust valve - Beginning of adjustment 5,550 rpm
Exhaust valve - end of adjustment with red auxiliary spring 7,200 rpm
Exhaust valve - end of adjustment with yellow auxiliary spring 7,900 rpm
Exhaust valve - end of adjustment with green auxiliary spring 8,400 rpm
Crankshaft bearing 1 grooved ball bearing/1 roller bearing
Conrod bearing Needle bearing
Piston pin bearing Needle bearing
Pistons Aluminum cast

KTM 125 SX Specifications

General

Engine Type	1-cylinder, 2-stroke engine
Displacement	124.8 cm³
Bore/Stroke	54 mm / 54.5 mm
Starter	Kickstarter
Transmission	6-speed
Rear Suspension	WP XACT shock absorber with linkage
Front Brake	Disc brake
Rear Brake	Disc brake
Ground Clearance	375 mm
Seat Height	950 mm
Cooling	Liquid cooled
Front Suspension	WP XACT USD, Ø 48 mm
Fuel System	Carburetor
Clutch	Wet multi-disc clutch
Frame	Central double-cradle type in chrome-molybdenum steel