Stihl MS 661 User Manual (English)

Other manuals for Stihl MS 661

Questions and Answers:

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Jacob RodriguezAug 18, 2025
Why Stihl MS 661 chain receives no oil?
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  Sara ChungAug 18, 2025
  If your Stihl chainsaw chain isn't getting oil, it could be due to several reasons. The oil inlet hole in the guide bar might be blocked, so try cleaning it. Alternatively, the intake hose or pickup body could be clogged, suggesting a replacement. A blocked valve in the oil tank could also be the culprit, requiring cleaning or replacement. Inspect the worm for worn teeth and replace if needed. Finally, the oil pump itself might be damaged or worn, necessitating a new oil pump.
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Alan TorresAug 20, 2025
Why Stihl MS 661 is losing chain oil?
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  Mark ByrdAug 20, 2025
  If your Stihl chainsaw is losing chain oil, the oil pump may be damaged or worn, requiring a replacement. Another cause could be a faulty gasket between the two halves of the crankcase, or a crack in the crankcase itself. In this case, replace the gasket and inspect the crankcase halves, replacing them if necessary.
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cynthia67Aug 23, 2025
What to do if Stihl MS 661 Chainsaw engine does not deliver full power or runs erratically?
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  Bradley WalkerAug 23, 2025
  If your Stihl chainsaw engine isn't delivering full power or is running erratically, consider these potential causes: worn or broken piston rings, which would need replacing; a carbonized muffler or spark arresting screen, suggesting cleaning or replacement; a dirty air filter, which should be cleaned or replaced; a kinked or torn fuel hose, which requires replacement or repositioning; or a decompression valve that isn't closed, which needs checking and possible replacement.
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Andrew AndersonAug 26, 2025
Why Stihl MS 661 Chainsaw engine does not start easily, stalls at idle speed, but operates normally at full throttle?
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  brownshannonAug 26, 2025
  If your Stihl chainsaw engine doesn't start easily, stalls at idle speed, but runs normally at full throttle, it could be due to damaged oil seals in the crankcase, requiring replacement. Alternatively, the crankcase might be leaking or damaged, necessitating sealing or replacement.
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Billy JonesAug 28, 2025
Why Stihl MS 661 Chainsaw engine runs roughly, misfires, temporary loss of power?
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  Tamara SanchezAug 28, 2025
  If your Stihl chainsaw engine runs roughly, misfires, or experiences temporary power loss, check the following: Ensure the spark plug boot is firmly attached; replace if necessary. Clean or replace a sooted or oily spark plug, and check the air filter if sooting recurs. Replace a loose ignition lead. Use the correct fuel/oil mixture, avoiding too much oil. Finally, ensure the air gap between the ignition module/control unit and flywheel is correct.
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Amanda McdonaldAug 30, 2025
What to do if Stihl MS 661 Chainsaw chain stops under full load?
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  Michael CoxAug 30, 2025
  If the saw chain on your Stihl chainsaw stops under a full load, it could be that the clutch shoes or clutch drum are badly worn. Consider installing a new clutch or a new clutch drum to resolve this issue.
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Anita HudsonSep 1, 2025
What to do if Stihl MS 661 chain runs while engine is idling?
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  Robyn SheltonSep 2, 2025
  If the chain on your Stihl chainsaw runs while the engine is idling, it might be because the engine idle speed is too high. Readjust the idle speed screw or check the M-Tronic system. Another possible cause is stretched or broken clutch springs. You can replace the clutch springs or install a new clutch.
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Hector RobinsonSep 4, 2025
How to fix Stihl MS 661 oil pump that delivers insufficient oil?
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  Miranda SparksSep 4, 2025
  If the oil pump on your Stihl chainsaw isn't delivering enough oil, it could be due to several reasons. The oil pump itself might be damaged or worn, requiring a replacement. Alternatively, the oil pump delivery rate may be set too low, so try adjusting it. A loose worm driver can also cause this issue, necessitating a new worm. Lastly, a damaged sealing ring between the oil pump and crankcase could be the problem, requiring replacement.
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Randall ParkerSep 6, 2025
Why Stihl MS 661 chain sprocket wears rapidly?
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  Billy KaiserSep 6, 2025
  If the chain sprocket on your Stihl chainsaw is wearing rapidly, it may be due to the chain not being properly tensioned; ensure you tension the chain as specified. Another cause could be the wrong chain pitch, so fit a chain of the correct pitch. Insufficient chain lubrication can also lead to rapid wear, so check the chain lubrication.
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Kelly WilliamsSep 9, 2025
What to do if Stihl MS 661 saw chain does not stop immediately when brake is activated?
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  wrightbreannaSep 9, 2025
  If the saw chain on your Stihl chainsaw doesn't stop immediately when the brake is activated, the chain brake spring may be stretched or broken, requiring a new brake spring. Also, the brake band might be stretched, worn, or broken, so fit a new brake band. A worn clutch drum can also cause this issue, so install a new clutch drum.