Stihl Hs 81 R Manual

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TCEnglish
19 In some countries the muffler is 
equipped with a spark arresting screen.
NCheck the spark arresting screen in 
the muffler after every 20 hours of 
operation, or if the engine is down 
on power or runs erratically at 
maximum speed.
NTake out the screws (1).
NRemove the exhaust pipe (2).NUse a 15 mm socket wrench to 
unscrew the spark arresting screen.
NClean the spark arresting screen. If 
the screen is damaged or heavily 
carbonized, fit a new one.
NRefit the spark arresting screen.
NFit the exhaust pipe.
NFit the screws.
Wrong fuel mix (too much engine oil in 
the gasoline), a dirty air filter and 
unfavorable running conditions (mostly 
at part throttle etc.) affect the condition 
of the spark plug. These factors cause 
deposits to form on the insulator nose 
which may result in trouble in operation.
If engine is down on power, difficult to 
start or runs poorly at idling speed, first 
check the spark plug.
NRemove spark plug – see Starting / 
Stopping the Engine.
NClean dirty spark plug.
NCheck electrode gap (A) and 
readjust if necessary – see 
Specifications.
NUse only resistor type spark plugs of 
the approved range.
Spark Arresting Screen in 
Muffler
Wait for the engine to cool down 
completely before performing this 
work.
Checking the Spark Plug
000BA002 KN 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TC English
20 Rectify problems which have caused 
fouling of spark plug:
NToo much oil in fuel mix.
NDirty air filter.
NUnfavorable running conditions, 
e.g. operating at part load.
Fit a new spark plug after approx. 100 
operating hours or earlier if the 
electrodes are badly eroded.Use STIHL gear lubricant for hedge 
trimmers (special accessory) to lubricate 
the blade drive gear.
After about 25 hours of operation:
NRemove the screw plug (1) from the 
gear housing on the underside of 
the unit.
NScrew the tube of grease (2) into the 
filler hole.
NSqueeze up to 1/4 oz (5 g) grease 
into the gearbox. Warning!
To reduce the risk of fire and burn injury, 
use only spark plugs authorized by 
STIHL. Always press spark plug boot (2) 
snugly onto spark plug terminal (1) of 
the proper size. (Note: If terminal has 
detachable SAE adapter nut, it must be 
attached.) A loose connection between 
spark plug boot and ignition wire con-
nector in the boot may create arcing that 
could ignite combustible fumes and 
cause a fire.
000BA036 TR
1
Lubricating the Gearbox
Do not completely fill the gearbox 
with grease. 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TCEnglish
21 NRemove the tube of grease (2).
NRefit the filler plug and tighten it 
down firmly.
To help prolong the wear life of the 
starter rope, observe the following 
points:
NPull the starter rope only in the 
direction specified.
NDo not pull the rope over the edge of 
the guide bushing.
NDo not pull out the rope more than 
specified.
NDo not allow the starter grip to snap 
back, guide it back into the housing 
slowly – see chapter on Starting / 
Stopping the Engine.
Have a damaged starter rope replaced 
by your dealer before it breaks 
completely. STIHL recommends that 
you have servicing and repair work 
carried out exclusively by an authorized 
STIHL servicing dealer.For periods of 3 months or longer
NDrain and clean the fuel tank in a 
well ventilated area.
NDispose of fuel properly in 
accordance with local 
environmental requirements. 
NRun the engine until the carburetor 
is dry – this helps prevent the 
carburetor diaphragms sticking 
together.
NClean the cutting blades, check 
condition and spray with STIHL 
resin solvent.
NFit the blade scabbard.
NThoroughly clean the machine – 
pay special attention to the cylinder 
fins and air filter.
NStore the machine in a dry, high or 
locked location. Out of the reach of 
children and other unauthorized 
persons.
Rewind StarterStoring the Machine 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TC English
22 When cutting performance and behavior 
begin to deteriorate, i.e. blades 
frequently snag on branches: 
Resharpen the cutting blades.
It is best to have the cutting blades 
resharpened by a dealer on a workshop 
sharpener. STIHL recommends a STIHL 
servicing dealer.
It is also possible to use a flat crosscut 
sharpening file. Hold the sharpening file 
at the prescribed angle (see 
Specifications).
NOnly sharpen the cutting edge – do 
not file blunt projecting parts of the 
cutting blade or the cutting blade 
guard (see Main Parts and 
Controls)
NAlways file towards the cutting 
edge.
NThe file only sharpens on the 
forward stroke – lift it off the blade 
on the backstroke.
NUse a whetstone to remove burr 
from cutting edge.
NRemove as little material as 
possible.
NAfter sharpening, clean away filing 
or grinding dust and then spray the 
cutting blades with STIHL resin 
solvent.
Maintenance Work
STIHL recommends that you have 
servicing and repair work carried out 
exclusively by an authorized STIHL 
servicing dealer.
Fuel Pickup Body in Tank
NHave the pickup body in the fuel 
tank replaced every year.
Spark Arrestor in Muffler
NIf the engine is down on power, 
have the spark arrestor in the 
muffler checked.
Sharpening Instructions
Do not operate your machine with 
dull or damaged cutting blades. 
This may cause overload and will 
give unsatisfactory cutting results.
Inspections and 
Maintenance by Dealer 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TCEnglish
23
Maintenance and Care
The following intervals apply to normal operating conditions only. If your daily work-
ing time is longer or operating conditions are difficult (very dusty work area, etc.), 
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
if required
Complete machineVisual inspection (condition, leaks)XX
CleanX
Control handle Check operationXX
Air filter (felt)CleanXX
ReplaceX
Air filter (paper)CleanXX
ReplaceXX
Pickup body in fuel tankHave checked by dealer
1)X
Have replaced by dealer
1)XXX
Fuel tank CleanXX
CarburetorCheck idle adjustmentXX
Readjust idleX
Spark plugReadjust electrode gapX
Replace after every 100 operating hours
Cooling inletsVisual inspectionX
CleanX
Spark arresting screen
2) in mufflerCheck after every 20 hours of operation
Have checked by dealer1)X
Have cleaned or replaced by servicing 
dealer
1)X
All accessible screws and nuts (not adjust-
ing screws)RetightenX
Antivibration elementsVisual inspectionX
Have replaced by dealer
1)XX 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TC English
24
Cutting bladesCleanX
SharpenX
Visual inspectionX
Have replaced by dealer
1)X
Adjust blade clearance
3)X
Gearbox lubricationCheck and replenish after every 25 
hours of operation
Safety labels ReplaceX
1)STIHL recommends a STIHL servicing dealer.2)not in all versions, market-specific3)not in all versions, market-specific or available as special accessory The following intervals apply to normal operating conditions only. If your daily work-
ing time is longer or operating conditions are difficult (very dusty work area, etc.), 
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
if required 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TCEnglish
25
Main Parts
5
13
8
9
3
10
7
20
17
2
442BA016 KN
1
4
6
#
11
1214
16
15
1819 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TC English
26 1Starter Grip
2Rear Handle
3Throttle Trigger Lockout
4Throttle Trigger
5Blocking Lever
6Filter Box Cover
7Fuel Pump
8Spark Plug Boot
9Front Handle
10Carburetor Adjusting Screws
11Starting Throttle Lock
12Stop Switch
13Fuel Filler Cap
14Fuel Tank
15Muffler
16Fan Housing
17Choke Lever
18Blade Scabbard
19Cutting Blade Guard
20Cutting Blades
#Serial Number
Definitions
1. Starter Grip
The grip of the pull starter, for 
starting the engine.
2. Rear Handle
The support handle for the hand, 
located at or toward the rear of the 
hedge trimmer.
3. Throttle Trigger Lockout
Must be depressed before the 
throttle trigger can be activated.
4. Throttle Trigger
Controls the speed of the engine.
5. Blocking Lever
Lever for rotating the rear handle.
6. Filter Box Cover
Covers the air filter.
7. Fuel Pump
Provides additional fuel feed for a 
cold start.
8. Spark Plug Boot
Connects the spark plug with the 
ignition lead.
9. Front Handle
Handle bar for the hand at front of 
hedge trimmer.
10. Carburetor Adjusting Screws
For tuning the carburetor.
11. Starting Throttle Lock
Keeps the throttle partially open 
during starting.
12. Stop Switch
Switches the engine’s ignition off 
and stops the engine.13. Fuel Filler Cap
For closing the fuel tank.
14. Fuel Tank
For fuel and oil mixture.
15. Muffler
Reduces engine exhaust noises 
and diverts exhaust gases away 
from operator.
16. Fan Housing
Polymer housing which encloses 
the power unit.
17. Choke Lever
Eases engine starting by enriching 
mixture.
18. Blade Scabbard
Covers cutter blades when hedge 
trimmer is not in use.
19. Cutting Blade Guard
Helps to reduce the risk of operator 
contact by the cutter blade.
20. Cutting Blades
Steel blades for cutting hedges and 
shrubs. 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TCEnglish
27
EPA / CEPA
The Emission Compliance Period 
referred to on the Emissions 
Compliance Label indicates the number 
of operating hours for which the engine 
has been shown to meet Federal 
emission requirements.
Category
CARB
The Emission Compliance Period used 
on the CARB-Air Index Label indicates 
the terms:
Engine
STIHL single cylinder two-stroke engine
Ignition System
Electronic magneto ignition 
(breakerless)
Fuel System
All position diaphragm carburetor with 
integral fuel pump
Weight
complete with cutting attachment, dry
HS 81 T
HS 81 TC
HS 81 R
Cutting BladesSpecifications
A = 300 hours
B = 125 hours
C = 50 hours
Extended = 300 hours
Intermediate = 125 hours
Moderate = 50 hours
Displacement: 1.39 cu. in. 
(22.7 cm
3)
Bore: 1.34 in. (34 mm)
Stroke: 0.98 in. (25 mm)
Engine power to 
ISO 7293:0.90 HP (0.7 kW) 
at 7,000 rpm
Idle speed: 2,800 rpm
Engine cut-off speed: 9100 rpmSpark plug (resistor 
type): Bosch USR 7 AC
Electrode gap: 0.02 in. (0.5 mm)
Fuel tank capacity: 15.6 fl.oz 
(0.46 L)
24 (600 mm) blade: 11.5 lbs 
(5.2 kg)
30 (750 mm) blade: 11.9 lbs 
(5.4 kg)
24 (600 mm) blade: 11.7 lbs 
(5.3 kg)
24 (600 mm) blade: 12.1 lbs 
(5.5 kg)
30 (750 mm) blade: 12.6 lbs 
(5.7 kg)Sharpening angle: 45° 
						

							HS 81 R, HS 81 RC, HS 81 T, HS 81 TC English
28 Contact your STIHL dealer for 
information regarding special 
accessories that may be available for 
your product.Users of this unit should carry out only 
the maintenance operations described 
in this manual. Other repair work may be 
performed only by authorized STIHL 
service shops.
Warranty claims following repairs can be 
accepted only if the repair has been 
performed by an authorized STIHL 
servicing dealer using original STIHL 
replacement parts.
Original STIHL parts can be identified by 
the STIHL part number, the { 
logo and, in some cases, by the STIHL 
parts symbol K. The symbol may 
appear alone on small parts.
Not for California
Your Warranty Rights and 
Obligations
The U.S. Environmental Protection 
Agency (EPA) and STIHL Incorporated 
are pleased to explain the Emission 
Control System Warranty on your 
equipment type engine. In the U.S. new 
1997 and later model year small off-road 
equipment engines must be designed, 
built and equipped, at the time of sale, to 
meet the U.S. EPA regulations for small 
non road engines. The equipment 
engine must be free from defects in 
materials and workmanship which 
cause it to fail to conform with U.S. EPA 
standards for the first two years of 
engine use from the date of sale to the 
ultimate purchaser.
STIHL Incorporated must warrant the 
emission control system on your small 
off-road engine for the period of time 
listed below provided there has been no 
abuse, neglect or improper maintenance 
of your small off-road equipment engine.
Your emission control system includes 
parts such as the carburetor and the 
ignition system. Also included may be 
hoses, and connectors and other 
emission-related assemblies.
Where a warrantable condition exists, 
STIHL Incorporated will repair your 
small off-road equipment engine at no 
Special AccessoriesMaintenance and RepairsSTIHL Incorporated 
Federal Emission Control 
Warranty Statement