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TECHNICAL SPECIFICATIONS – ENGINE 125/144/250 SX 2008»
ENGINE 125 SX 144 SX 250 SX
Design Liquid-cooled, single-cylinder, two-stroke engine with intake and exhaust control
Piston displacement 124.8 ccm 143.6 ccm 249 ccm
Bore / stroke 54 / 54.5 mm 54 / 58.4 mm 66.4 / 72 mm
Fuel
unleaded fuel with at least RON 95 (USA = Premium PON 91), mixed with high grade two stroke oil
Oil / gasoline ratio 1:40 1:40 1:60
when using high grade, two- stroke oil (Motorex Cross Power 2T).
Crankshaft bearing 1 deep-groove ball bearing / 1 cylinder roller bearing
Connecting rod bearing needle bearing
Piston pin bearing needle bearing
Piston cast aluminum
Piston ring 2 half keystone rings 2 half keystone rings two plain compression rings
Dimension „X“ 0.0 mm 0.0 mm 0.0 + 0.1 mm
Ignition timing
1.4 mm (0.055 in) BTDC 1.4 mm (0.055 in) BTDC
1.9 mm (0.074 in) BTDC
Spark plug NGK BR9 ECMVX NGK BR9 ECMVX NGK BR8 ECM
Electrode gap 0,60 mm
Dimension „Z“ 43.5 mm (1.68 in) 43.1 mm (1.69 in) 47.5 mm (1.87 in)
Exhaust control start open
- - 5500/min
Exhaust control fully open
- -
7000/7500/7900/min (red/yellow/green spring)
Primary drive straight cut spur gears
Primary ratio 23 : 73 23 : 73 26 : 72
Available chain sprockets
13t /14t for chain 5/8 x 1/4”
Clutch multiple disc clutch in oil bath, hydraulically operated
Motorex Hydraulic Fluid 75 Motorex Hydraulic Fluid 75 Motorex brake fluid DOT 5.1
Transmission 6 speed, claw actuated 6 speed, claw actuated 5 speed, claw actuated
Gear ratio
1st gear 13 : 32 „1S32“ 13 : 32 „1S32“ “1S14” 14 : 28 “1S28”
2nd gear „2S15“ 15 : 30 „2S30“ „2S15“ 15 : 30 „2S30“ “2S15” 15 : 24 “2S24”
3rd gear „3S17H“ 17 : 28 „3S28H“ „3S17H“ 17 : 28 „3S28H“ “3S18” 18 : 24 “3S24”
4th gear „4S20H“ 20 : 28 „4S28“ „4S20H“ 20 : 28 „4S28“ “4S21” 21 : 24 “4S24”
5th gear „5S19H“ 19 : 23 „5S23H” „5S19H“ 19 : 23 „5S23H” “5S22” 22 : 21 “5S21”
6th gear „6S22H“ 22 : 24 „6S24H” „6S22H“ 22 : 24 „6S24H”
Gear lubrication 0,7 liter Motorex Top Speed 4T 15W50
Available chain sprockets
13Z / 14Z für Kette 5/8 x 1/4"
Coolant 1.2 litres, 50% anti freeze, 50% distilled water, at least -25 °C (-13 °F)
Ignition system KOKUSAN 2K-1 KOKUSAN 2K-1 stator 2K-1/flywheel 2K-2
Carburetor flat-slide carburetor, carburetor setting see table
Air-filter wet foam type air filter insert
(upper edge piston-
upper edge cylinder)
(height of the
control flap)
BASIC CARBURETOR SETTING
125 SX 144 SX 250 SX
Carburetor Keihin PWK 39 Keihin PWK 39 Keihin PWK 36 S AG
Carburetor setting mark 98SA0/98SA1 FJ011 FK0160
Main jet 188 (185/190) 202 (200, 205) 158 (155, 160)
Idling jet 45 (48) 45 (48) 45 (42)
Starting jet 85 85 85
Jet needle R1469D (R1470D) R1471H (R1470H, R1472H) N1EI (N1EH)
Needle position from top II III III
Throttle valve 5.5 5.5 6.5
Air adjustment srew open
1.5 1.5 1