SRM-420ES, SRM-420TES
T410S, B410S
T410TS, B410TS
4
SERVICE INFORMATION
4
1-2 Technical data
Model
SRM-420ES
T410S, B410S
SRM-420TES
T410TS, B410TS
Engine
Compression pressure MPa (kgf/cm
2
) (psi) 0.92 (9.4) (132)
Clutch engagement speed r/min 3,700
Ignition system
Spark plug gap mm(in) 0.6 - 0.7 (0.024 - 0.028)
Spark test Tester gap w/ spark plug mm(in) 4.0 (0.16)
Tester gap w/o spark plug mm(in) 6.0 (0.24)
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 8,500 r/min °BTDC 29
Carburetor
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
Tool to adjust mixture needles D-shaped (L) P/N X645-000031
Carburetor adjustment
Cutting head preparation
Nylon line cutter DS-5 B6
Line length*
1
190 mm without shield 240 mm without shield
1) Initial setting H mixture needle turn out 3
L mixture needle turn out 2 3/8
Throttle adjust screw turn in*
2
2 1/8
Engine warm-up Idle - WOT : Total sec. 10 - 50 : 180
2) Find idle maximum speed Adjust L mixture needle to maximum idle speed*
3
3) Set idle maximum speed w/ TAS r/min 3,550
4) Set idle speed
by turning L mixture needle CCW
r/min 2,750
5) Find WOT maximum speed r/min Adjust H mixture needle to maximum WOT speed
6) WOT setting
Turn H mixture needle CCW
to decrease WOT speed by : 120
r/min
7) Verify fi nal engine speed with standard equipment Idle: 2,400 - 3,200
r/min
WOT: 9,500 - 10,500*
WOT: 10,500 - 11,500**
WOT: 9,800 - 11,000*
8) Verify clutch engagement speed
Confi rm clutch engagement speed.
If it is less than 1.25 times the idle speed, adjust
the idle speed by turning TAS CCW.
BTDC:
Before top dead center.
WOT:
Wide open throttle
CCW:
Counterclockwise
TAS:
Throttle adjust screw
* With Nylon line head and shield ** With 3-tooth blade (255 mm)
*
1
From eyelet on nylon head
*
2
Set Throttle adjust screw to the point that its tip just contacts throttle plate before initial setting.
*
3
If clutch engages during adjustment process 2), decrease engine speed by turning TAS CCW until clutch
disengages and then redo 2).
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