SERVICE INFORMATIONSRM-420ES
3
1-2 Technical data
Model
SRM-420ES (L) SRM-420ES (U)
Engine
Idling speed r/min 2,800 +/- 400
Wide open throttle speed r/min 9,500 - 10,500* 10,500 - 11,500**
Clutch engagement speed r/min 3,700
Engagement Limit
†
r/min Less 3,300 or over 4,300
Compression pressure MPa (kgf/cm
2
) (psi) 0.92 (9.4) (132)
Ignition system with stop holding function
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Minimum secondary voltage at 1500 r/min kV 22
Primary coil resistance
MΩ 2.4 -2.9
(Red Probe on stop terminal of module)
Secondary coil resistance Ω 930 - 970
Pole shoe air gaps mm(in) 0.3 - 0.4 (0.012 - 0.016)
Ignition timing at 3,000 r/min °BTDC 12
at 8,000 r/min °BTDC 25
at 10,000 r/min °BTDC 23
Carburettor
Venturi Size 12.7 (0.50)
Throttle Bore 14.3 (0.56)
Idle adjust screw initial setting turns in*** 2 1/8
L mixture needle initial setting turns out 2 3/8
H mixture needle initial setting turns out 3
Test Pressure, minimum MPa (kgf/cm
2
) (psi) 0.05 (0.5) (7.0)
Metering lever height mm(in) 1.65 (0.06) lower than diaphragm seat
BTDC: Before top dead centre.
*With Nylon line cutter and shield.
**With 3-tooth blade (255 mm).
*** Set idle adjust screw to the point that its tip just contacts throttle plate before initial setting.
†
If clutch engagement speed is lower than lower service limit speed or higher than uper service limit speed,
replace clutch assembly with new one.
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