Technical Information · issue 20 of 2000
New Model HL 73 Hedge Trimmer
IssueTI 20/2000
Full text
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Technical Information
20.2000
New Model HL 73 Hedge Trimmer - Series 4235
Contents
1. Technical Description
2. Specifications
3. Cutting Blades
4. Accessories
5. Service Accessories
6. Repairs
7. Spare Parts
The new STIHL HL 73 hedge trimmer complies with scavenging losses (see “1. Technical Description“).
the CARB II standards. It is built on the basis of a The controls, handle system, drive tube, gearbox
new engine (series 4141 powerhead) which and cutting blades are exactly the same as those of
features a stratified charging system. the STIHL HL 75.
In this stratified charging system a layer of air
Recommended applications are the same as those
containing no fuel is laid in front of and partially over
of the HL 75.
the combustible mixture. This cushion of air reduces
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1. Technical Description
Controls, handle system, drive tube, gearbox and cutting attachment are the same as those of the HL 75.
Stratified charged engine
380TI004 KN
Compression and induction
. A layer of air free from fuel is laid on top of the combustible mixture through additional reed valves in the
cylinder’s transfer ports
380TI005 KN
Combustion
. Crankcase pressure increases and causes the reed valves in the transfer ports to close
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Technical Information 20.2000 Page 3
380TI006 KN
Scavenging the cylinder (inlet)
. The fuel-free layer of air flows into the cylinder first
380TI007 KN
Scavenging the cylinder (outlet)
. Scavenging losses consist mainly of air
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380TI008 KN
Induction and compression
. Diaphragm valves in cylinder’s transfer ports open again
2. Specifications
2.1 Powerhead
2.1.1 Engine
Single cylinder two-stroke engine
Displacement: 1.55 cu.in (25.4 cm3)
Bore: 1.34 in (34 mm )
Stroke: 1.10 in (28 mm)
Engine power to 1.2 HP (0.9 kW)
ISO 8893: at 7,000 rpm
Engine speeds: see 2.1.2
Rewind starter: Single pawl system
Starter rope: 0.12 in (3 mm) dia.,
31.5 in (800 mm) long
Clutch engages at: 4,100 ±200 rpm
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Technical Information 20.2000 Page 5
2.1.2 Fuel System
Carburetor: All position diaphragm carburetor with integral fuel pump
Idle speed screw LA (standard setting) Open 6 full turns
Idle speed 3,000 rpm
Maximum engine speed without cutting attachment
- without speed governor 12,900 ±800 rpm
- with speed governor in ignition module 10,500 ±500 rpm
Fuel tank capacity: 1.5 US pt (0.7 L)
Fuel mixture: Mid-grade (89 octane) brand-name gasoline and brand-name two-stroke engine oil
Mix ratio: 50:1 with STIHL 50:1 two-stroke engine oil
2.1.3 Ignition System
Ignition module
- Start of prod.only: without speed governor
- Thereafter: with speed governor
Spark plug NGK CMR 7 A
(suppressed): 0000 400 7007
Electrode gap: 0.020 - 0.024 in
(0.5 - 0.6 mm)
Spark plug thread: M10x1.0
0.37 in (9.5 mm) long
2.2 Dimensions / Weight
2.2.1 Overall length
HL 73: approx. 7ft 10in
(240 cm)
HL 73 K: approx. 6ft 7in
(200 cm)
2.2.2 Weight
HL 73
- with 0° / 30° cutter bar: 14.3 lbs ( 6.5 kg)
- with adjustable cutter bar: 15 lbs (6.8 kg)
HL 73 K
- with 0° / 30° cutter bar: 13.7 lbs (6.2 kg)
- with adjustable cutter bar: 14.3 lbs (6.5 kg)
3. Cutting Blades
Cutting length 23 in. double-edged, ground to an
angle of 45°
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4. Accessories
Part Name Part No. Application
Spark plug NGK CMR 7A 0000 400 7007 Engine
ElastoStart™ 0000 190 3400 Rewind starter (grip with rope)
Starter rope 0000 195 8200 Rewind starter, also for ElastoStart™
Flat sharpening file 0814 250 1000 Resharpening the cutting blades
STIHL gear lubricant for hedge Blade drive, drive shaft in tube
trimmers
- 2.8 oz (80 g) tube 0781 120 1109
- 8 oz (225 g) tube 0781 120 1110
STIHL gear lubricant for Angle drive
brushcutters
- 2.8 oz (80 g) tube 0781 120 1117
- 8 oz (225 g) tube 0781 120 1118
5. Service Accessories
5.1 Special Servicing Tools
The special servicing tools for the engine are listed in the service manual for the STIHL series 4141 powerhead.
For all other parts see service manual for models FS 75, 80, 85; HL 75.
5.2 Servicing Aids
Part Name Part No. Application
Carburetor parts kit 4141 007 1002 Walbro WYA1
Set of gaskets 4141 007 1003 Engine
Electrician’s repair kit 5910 007 1050 Electrical system
Standard commercial solvent- Cleaning crankshaft stub
based degreasant containing no
chlorinated or hydrogenated
hydrocarbons
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6. Repairs
If the unit is started up in the course of repairs or maintenance work, it is essential to strictly observe
all local and national safety regulations and the safety precautions outlined in the owner’s manual.
6.1 Carburetor Adjustment
Standard setting
. Check cutting blades and clean if necessary
(clean, move freely, not warped).
. Check air filter and fit a new one if necessary.
. Inspect spark arresting screen in the muffler and
clean or replace as necessary.
. Carefully back off the idle speed screw (LA)
counterclockwise until the end of the screw
(arrow) just disappears, then turn it six full turns
clockwise.
LA
Adjusting idle speed
. Carry out standard setting.
. Start and warm up the engine.
Engine stops while idling:
. Turn the idle speed screw (LA) slowly clockwise
until engine runs smoothly - the cutting blades
must not move.
Cutting blades move while engine is idling:
. Turn the idle speed screw (LA) counter-
clockwise until the cutting blades stop moving
380TI010 KN
and then turn the screw about another two full
turns in the same direction (counterclockwise).
6.2 Tightening torques
The tightening torques for the powerhead are listed in the service manual for the STIHL series 4141
powerhead. For all other parts service manual for models FS 75, 80, 85; HL 75.
Warning: Torque down spark plug to max. 11ft.lb (15 Nm) only when the engine is cold.
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6.3 Service Note
The service manual for the STIHL series 4141 Code Type of Repair HL 73
powerhead can be used for servicing and repair HL 73 K
procedures on the HL 73 powerhead. For all other
parts see service manual for models FS 75, 80, 85; 1 Crankcase, Crankshaft, 2.0
HL 75. Crankshaft Bearings
The above service manuals do not include the
3 Crankcase Gasket/Sealing 2.0
chapters "Servicing the Carburetor",
"Troubleshooting" or any repairs involving standard 4 Crankshaft Seals (includes 1.0
procedures. Such procedures are described in pressure & vacuum testing)
separate handbooks, i.e. “Carburetors” and 5 Cylinder and/or Piston 1.2
"Standard Repairs, Troubleshooting". 6 Ignition Module 0.5
7 Fuel Hose 0.5
6.4 Repair Times
8 Replace Gear Box Cover 0.4
The specified repair times assume that the work is 9 Repair/Rebuild Carburetor 0.8
performed by trained personnel in a properly
10 Replace Carburetor, Carburetor 0.4
equipped service workshop.
Jet (if tried to repair use code 9)
11 Front Handle, Throttle Control, 0.6
The repair times are given in tenths of an hour Throttle Cable
(0.1 = 6 minutes). 12 Recoil Starter 0.5
13 Clutch 0.7
14 Cutter Bar 0.5
Note: This table for model HL 73 can be added to
15 Muffler 0.4
the STIHL repair times tables manual.
16 Air Filter, Filter Cover, Tank Vent, 0.4
Fuel Filter, Spark Plug, Cutting
Attachment, Miscellaneous Minor
Repairs
7. Spare Parts 17 Stop Switch 0.5
18 Fuel Tank 0.4
A separate illustrated parts list is available for the
19 Repair Gear Box, Gears/Bearings 0.8
new model.
20 All Other Repairs 0.5
✂
© 2000 Andreas STIHL AG & Co. Technical Documentation
Waiblingen D1/MTK-sc 7058
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Extracted from the manufacturer's 2012 service catalogue. Most of these PDFs embed fonts with a shifted character map, so the text above was recovered rather than copied — read it as a faithful but imperfect transcription, and treat the page image above each block as the authority where the two disagree — the figures exist only there, because they are vector drawings that text extraction cannot keep.