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21 TECHNICAL DATA 99

21.1 Engine

21.1.1 125 SX EU, 125 SX USA

Design 1-cylinder 2-stroke engine, water-cooled, with reed intake and

exhaust control

Displacement 124.8 cm³ (7.616 cu in)

Stroke 54.5 mm (2.146 in)

Bore 54 mm (2.13 in)

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) 43.7 mm (1.72 in)

Primary transmission 23:73

Clutch Multidisc clutch in oil bath/hydraulically activated

Gearbox 6-gear, claw shifted

Transmission ratio

1st gear 13:32

2nd gear 15:30

3rd gear 17:28

4th gear 20:28

5th gear 19:23

6th gear 22:24

Ignition Contactless controlled fully electronic ignition with digital igni-

tion adjustment, type Kokusan

Ignition point (BTDC) 1.4 mm (0.055 in)

Spark plug NGK BR9 ECMVX

Spark plug electrode gap 0.60 mm (0.0236 in)

Starting aid Kick starter

21.1.2 150 SX EU, 150 SX USA

Design 1-cylinder 2-stroke engine, water-cooled, with reed intake and

exhaust control

Displacement 143.6 cm³ (8.763 cu in)

Stroke 58.4 mm (2.299 in)

Bore 56 mm (2.2 in)