Stihl MS 391

8 MS 311, MS 391
3. Troubleshooting
3.1 Clutch
Condition Cause Remedy
Saw chain stops under load at full
throttle
Clutch shoes badly worn Install new clutch
Clutch drum badly worn Install new clutch drum
Saw chain rotates at idle speed Engine idle speed too high Readjust with idle speed screw
LA (counterclockwise)
Clutch springs stretched or fatigued Replace the clutch springs or install
new clutch
Clutch spring hooks broken Replace the clutch springs or install
new clutch
Loud noises Clutch springs stretched or fatigued Replace the clutch springs or install
new clutch
Needle cage damaged Fit new needle cage
Clutch shoe retainer broken Install new retainer or clutch
Clutch shoes and carrier worn Install new clutch