Instruction Manual
Table Of Contents
- STIHL MS 661 C-M
- 1 Introduction
- 2 Guide to Using this Manual
- 3 Overview
- 4 Safety Precautions
- 5 Preparing the Saw for Operation
- 6 Assembling the Saw
- 7 Engaging and Disengaging the Chain Brake
- 8 Mixing Fuel and Refueling the Chainsaw
- 9 Starting and Stopping the Engine
- 10 Checking the Saw
- 11 Operating the Saw
- 12 After Finishing Work
- 13 Transporting
- 14 Storing
- 15 Cleaning
- 16 Maintenance
- 17 Repairing
- 18 Troubleshooting
- 19 Specifications
- 20 Bar and Chain Combinations
- 21 Spare Parts and Accessories
- 22 Disposal
- 23 EC Declaration of Conformity

► If the air filter (3) is damaged. Install a new air
filter (3).
WARNING
■ Cleaning agent may cause irritation if it con‐
tacts the skin or eyes.
► Observe the information supplied with the
cleaning agent.
► Avoid contact with cleaning agents.
► In case of contact with the skin: Wash affec‐
ted areas with plenty of water and soap.
► In case of contact with the eyes: Rinse eyes
with plenty of water for at least 15 minutes
and seek medical advice.
►
Spray the outside and inside of the air filter
(3) with STIHL special cleaner or a cleaning
agent with a pH value higher than 12.
► Allow STIHL special cleaner or cleaning agent
to act for 10 minutes.
► Use a soft brush to clean the outside of the air
filter (3).
► Rinse the outside and inside of the air filter (3)
under running water.
► Allow air filter (3) to dry in the air.
0000-GXX-5820-A0
3
1
2
► Push the air filter (3) into place by hand.
► Fit the filter cover (2).
► Rotate the filter cover lock (1) clockwise until
you hear a click.
The filter cover lock (1) is secure.
15.4 Cleaning the Spark Plug
► Shut off the engine and engage the chain
brake.
► Allow chainsaw to cool down.
2
1
0000-GXX-A379-A0
► Remove the filter cover (1).
► Pull off the spark plug boot (2).
► If area around the spark plug is dirty: Clean it
with a damp cloth.
► Unscrew the spark plug.
► Clean the spark plug with a damp cloth.
► If the spark plug is corroded: Install a new
spark plug.
2
0000-GXX-A380-A0
► Fit the spark plug and tighten it down firmly.
► Press the spark plug boot (2) firmly home.
► Fit the filter cover (1).
16 Maintenance
16.1 Maintenance Intervals
The maintenance intervals are dependent on the
environmental and operating conditions. STIHL
recommends the following maintenance inter‐
vals:
Chain brake
► Have the chain brake serviced by a STIHL
servicing dealer at the following intervals:
–
Full-time usage: every 3 months
–
Part-time usage: every 6 months
–
Occasional usage: every 12 months
After every 100 hours of operation
► Install a new spark plug.
Weekly
► Check the chain sprocket.
► Check and deburr the guide bar.
► Check and sharpen the saw chain.
Monthly
► Clean the air filter.
► Have oil tank cleaned by a STIHL servicing
dealer.
► Have fuel tank cleaned by a STIHL servicing
dealer.
► Have pickup body (filter) in fuel tank cleaned
by a STIHL servicing dealer.
Every 12 months
► Have pickup body (filter) in fuel tank replaced
by a STIHL servicing dealer.
English 16 Maintenance
24 0458-759-0121-D. VA0.A21.