Stihl TS 420 User Manual

1TS 410, TS 420
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© ANDREAS STIHL AG & Co. KG, 2007
RA_370_00_01_03
1. Introduction 3
2. Safety precautions 5
3. Specifications 6
3.1 Shortblock 6
3.2 Fuel system 6
3.3 Ignition system 6
3.4 Cutting wheels 6
3.5 Tightening torques 7
4. Troubleshooting 9
4.1 Clutch 9
4.2 Cast arm with guard 10
4.3 Rewind starter 11
4.4 Ignition system 12
4.5 Carburetor 14
4.6 Engine 17
5. Cast arm with guard 18
5.1 Water system 18
5.2 Cast arm with guard 19
5.3 Testing radial and axial
truth of running 24
5.4 Test sequence 25
5.5 Ribbed poly V-belt 26
5.6 Tensioner 27
5.7 Starter cup 28
6. Clutch 30
6.1 Belt pulley /
clutch drum 31
6.2 Studs for securing the
cast arm with guard 32
7. Shortblock 33
7.1 Muffler / spark arresting
screen 33
7.2 Leak testing 34
7.2.1 Preparatory steps 34
7.2.2 Vacuum test 34
7.2.3 Pressure test 35
7.3 Oil seals 36
7.4 Removing and installing
the shroud 37
7.5 Cylinder 39
7.6 Crankshaft 41
7.6.1 Removal and
installation 41
7.6.2 Grooved ball
bearing / crankcase 46
7.7 Piston 47
7.7.1 Removal 47
7.7.2 Installation 48
7.8 Piston rings 50
7.9 Decompression valve 50
8. Ignition system 51
8.1 Ignition module 51
8.1.1 Removal and
installation 51
8.2 Ignition timing 53
8.3 Testing the ignition
module 53
8.4 Spark plug boot 54
8.5 Flywheel 55
8.6 Short circuit wire /
switch 56
8.6.1 Testing 56
8.6.2 Removal and
installation 56
8.7 Troubleshooting,
ignition system 58
9. Rewind starter 61
9.1 General 61
9.2 Removal and
installation 61
9.3 Pawl 61
9.4 Rope rotor 62
9.5 Starter rope /
starter grip 63
9.6 Tensioning the rewind
spring 64
9.7 Replacing the rewind
spring 65
10. Repairing the
AV system 67
10.1 AV spring on the
handlebar 67
10.2 AV spring in the
support 68
10.3 AV spring at the bottom
of the crankcase 68
10.4 AV spring on the
carburetor 69
10.5 Handlebar 69
10.6 Rubber buffers /
support 71
11. Actuating levers 73
11.1 Switch shaft /
choke lever 73
11.1.1 Switch shaft, removal
and installation 73
11.2 Throttle trigger /
trigger interlock, removal
and installation 74
11.2.1 Choke lever / holder,
removal and
installation 76
Contents

Stihl TS 420 Specifications

General

Engine Power	4.4 bhp
Weight	21.2 lbs
Arbor Size	20 mm
Maximum Wheel Size	350 mm
Maximum Cutting Depth	125 mm
Displacement	66.7 cc (4.1 cu. in.)
Fuel Capacity	710 cc