22 TECHNICAL DATA
128
22.1 Engine
Design 1-cylinder 4-stroke engine, water-cooled
Displacement 349.7 cm³ (21.34 cu in)
Stroke 57.5 mm (2.264 in)
Bore 88 mm (3.46 in)
Compression ratio 14.6:1
Idle speed 2,250 … 2,350 rpm
Control DOHC, four valves controlled via cam lever, drive via
timing chain
Valve diameter, intake 36.3 mm (1.429 in)
Valve diameter, exhaust 29.1 mm (1.146 in)
Valve clearance
Intake at: 20 °C (68 °F) 0.08 … 0.15 mm (0.0031 … 0.0059 in)
Exhaust at: 20 °C (68 °F) 0.12 … 0.19 mm (0.0047 … 0.0075 in)
Crankshaft bearing 2 cylinder bearings
Conrod bearing Slide bearing
Piston pin bearing Bearing bush
Pistons Forged light alloy
Piston rings 1 compression ring, 1 oil scraper ring
Engine lubrication Pressure circulation lubrication with 2 trochoidal
pumps
Primary transmission 24:72
Clutch Multidisc clutch in oil bath/hydraulically activated
Gearbox (All SX‑F models) 5-gear transmission, claw shifted
Gearbox (XC‑F US) 6-gear transmission, claw shifted
Transmission ratio (All SX‑F models)
first-gear 14:28
second-gear 16:26
third-gear 18:24
fourth-gear 21:24
fifth-gear 22:21
Transmission ratio (XC‑F US)
first-gear 13:33
second-gear 16:30
third-gear 18:26
fourth-gear 22:26
fifth-gear 23:23
sixth-gear 26:22
Alternator 12 V, 70 W
Ignition Contactless controlled fully electronic ignition with
digital ignition adjustment
Spark plug NGK LMAR9AI-10
Spark plug electrode gap 1.0 mm (0.039 in)
Cooling Water cooling, permanent circulation of coolant by
water pump
Starting aid Starter motor