21 TECHNICAL DATA 166
21.1 Engine
21.1.1 125 Duke
Design 1-cylinder 4-stroke engine, water-cooled
Displacement 125 cm³ (7.63 cu in)
Stroke 47.2 mm (1.858 in)
Bore 58 mm (2.28 in)
Compression ratio 12.8:1
Control DOHC, 4 valves controlled via cam lever, chain drive
Valve diameter, intake 22.5 mm (0.886 in)
Valve diameter, exhaust 19 mm (0.75 in)
Valve clearance, intake, cold 0.08… 0.12 mm (0.0031… 0.0047 in)
Valve clearance, exhaust, cold 0.13… 0.17 mm (0.0051… 0.0067 in)
Crankshaft bearing Two ball bearings
Conrod bearing Sleeve bearing
Pistons Cast light alloy
Piston rings 1 compression ring, 1 tapered compression piston ring, 1 oil
scraper ring
Engine lubrication Pressure circulation lubrication with one rotary pump
Primary transmission 22:72
Clutch Clutch in oil bath/mechanically activated
Transmission 6-gear, claw shifted
Transmission ratio
1st gear 12:34
2nd gear 15:31