STIHL MS 661 Problems: Fixes and Troubleshooting Tips

The STIHL MS 661 chainsaw is a popular choice for professionals and homeowners alike, known for its reliability and impressive cutting power.

However, like any mechanical tool, it is not immune to occasional issues. Understanding some of the common problems faced by users of the MS 661 can help in diagnosing and resolving these issues efficiently.

One of the typical concerns with the STIHL MS 661 is its starting difficulties. Users may experience trouble getting the engine to turn over, which can be frustrating and time-consuming. Identifying the causes behind this problem, such as fuel issues, spark plug failure, or a flooded engine, can enable users to take the appropriate troubleshooting steps.

Another issue that may arise with the MS 661 relates to a decrease in cutting performance. Users might notice a slow cutting speed, a dull chain, or increased vibrations during operation.

Careful inspection of the chainsaw’s components, such as the chain tension and sharpness, guide bar, and air filter, can help pinpoint the root cause of these performance issues.

Common Issues and Solutions

Engine Performance Problems

Engine performance is a crucial aspect of any chainsaw, and STIHL MS 661 is no exception. Some common issues with engine performance include hard starting, rough idling, and poor acceleration.

To resolve these problems, users can try the following:

  • Checking and cleaning the air filter regularly
  • Inspecting the spark plug for damage and proper gap
  • Ensuring a proper fuel-to-oil mixture for optimal engine lubrication

Chain Brake Issues

A chain brake is an important safety feature on a chainsaw. If the chain brake malfunctions or doesn’t engage properly, it might cause serious injuries.

To tackle chain brake issues, consider:

  • Lubricating the brake band and clutch drum
  • Ensuring the brake band is in good condition and not worn out
  • Regularly inspecting the brake spring for any damages

Fuel Line Failures

Fuel line failures can cause a chainsaw to stop functioning or lead to erratic performance.

To avoid fuel line issues and ensure smooth operation, follow these steps:

  • Routinely check for any cracks or damages in the fuel line
  • Replace the fuel line if necessary
  • Make sure the fuel filter is clean and functioning well

Adjustment Screw Difficulties

Adjustment screws on the STIHL MS 661 can cause problems if they become difficult to turn or don’t hold their position.

Solutions for adjustment screw difficulties include:

  • Using a small amount of lubricant on the screws to make them easier to turn
  • Checking for any debris or dirt that might be affecting the screws’ movement
  • Confirming the threads on the screws and corresponding holes are not damaged

Regular Maintenance and Prevention

Proper Chain Tension

If the chain is too tight or too loose, it can cause various problems, including increased wear, reduced cutting efficiency, and potential safety hazards.

Adjusting the chain tension is a simple task that should be done periodically.

To do so, first, release the chain brake and then loosen the adjustment screws on the side of the chainsaw. Adjust the chain tension by turning the adjusting wheel until there is only a slight sag when lifting the chain away from the guide bar.

Tighten the adjustment screws and re-engage the chain brake before testing the tension.

Spark Plug Care

Caring for the spark plug is another essential part of STIHL MS 661 chainsaw maintenance. A properly functioning spark plug will help the engine run smoothly and efficiently.

Remove the spark plug periodically to inspect for damage, deposits, or wear. If necessary, clean the spark plug using a brush and replace it with a new one if it’s worn out or damaged.

Cleaning and Replacing Fuel Lines

Over time, fuel lines can become clogged, reducing the flow of fuel to the engine, which can result in decreased performance.

To clean the fuel lines, remove the fuel tank and empty it. Use a clean rag or brush to wipe away any debris that has accumulated on the fuel lines, and replace the fuel filter if needed.

Inspect the condition of the fuel lines as well, and if any damage or wear is observed, replace them with new lines to maintain efficient fuel flow to the engine.

Troubleshooting Tips

Identifying Positions and Components

In order to properly address potential problems with a STIHL MS 661 chainsaw, it’s essential to familiarize yourself with the positions and components of the tool.

Refer to the user manual for a comprehensive understanding of the chainsaw’s parts and their functions. Some key components that may require attention include the carburetor, ignition system, chain tension, and air filter.

  • Carburetor: Ensuring that the carburetor is clean and properly adjusted can help avoid performance issues.
  • Ignition System: Regularly inspect the spark plug and ignition coil for wear or damage, and replace them as needed.
  • Chain Tension: Checking and adjusting the chain tension frequently can help prolong the lifespan of the chainsaw.
  • Air Filter: A clean air filter is essential for optimal performance, so be sure to remove and clean it regularly.

When to Seek Professional Help

While some STIHL MS 661 issues may be simple enough to resolve without professional assistance, there are situations where it’s best to consult an expert.

Here are a few scenarios where it is wise to seek help:

  1. Persistent engine problems: If the chainsaw’s engine continues to struggle or stall despite following all recommended troubleshooting steps, it may be necessary to have a professional diagnose the issue.
  2. Difficulty starting: If the chainsaw is consistently difficult to start, even after replacing the spark plug and checking the fuel lines, there may be a more serious underlying issue that requires professional attention.
  3. Unexplained noises: Strange noises emanating from the chainsaw during operation, such as rattling or grinding, can be a sign of internal damage that should not be ignored.

In any of these cases, it’s important to seek the help of a qualified technician or take the chainsaw to an authorized STIHL service center for evaluation and repair.

Remember that safety should always be the top priority when working with a chainsaw. Ensure that the chainsaw is secured in the proper position when troubleshooting.

Leave a Comment