21 TECHNICAL DATA
130
21.1 Engine
21.1.1 All SX models
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)
Hole 66.4 mm (2.614 in)
Exhaust valve, beginning of adjustment 5,500 rpm
Crankshaft bearing 1 grooved ball bearing/1 roller bearing
Conrod bearing Needle bearing
Piston pin bearing Needle bearing
Piston Cast aluminum
Piston rings 2 half keystone rings
X distance (upper edge of piston to upper edge of
cylinder)
0 … 0.10 mm (0 … 0.0039 in)
Z distance (height of control flap) 49.0 mm (1.929 in)
Primary transmission 26:73
Clutch Multidisc clutch in oil bath/hydraulically activated
Transmission 5-gear, claw shifted
Transmission ratio
First gear 14:28
Second gear 16:26
Third gear 18:24
Fourth gear 21:24
Fifth gear 22:21
Ignition system Contactless controlled, fully electronic ignition with
digital ignition adjustment, type Kokusan
Spark plug NGK BR 8 ECM
Spark plug electrode gap 0.60 mm (0.0236 in)
Starting aid Kick starter
21.1.2 250 XC US
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)
Hole 66.4 mm (2.614 in)
Exhaust valve, beginning of adjustment 5,500 rpm
Crankshaft bearing 1 grooved ball bearing/1 roller bearing
Conrod bearing Needle bearing
Piston pin bearing Needle bearing
Piston Cast aluminum
Piston rings 2 half keystone rings
X distance (upper edge of piston to upper edge of
cylinder)
0 … 0.10 mm (0 … 0.0039 in)