Stihl TS 420 - Page 16

15TS 410, TS 420
Problem Cause Remedy
Engine will not idle, idle speed too
high
Throttle shutter opened too wide by
idle speed screw LA
Set idle speed screw LA correctly
Oil seals / crankcase leaking Seal oil seals / crankcase, replace if
necessary
Air valve soiled
– air valve does not close
Clean air valve, replace if
necessary
Air valve moves stiffly Check air valve, replace if
necessary
Throttle rod moves stiffly
– throttle shutter does not close
Restore easy movement of throttle
rod
Engine stops when idling Idle jet bores or ports blocked Clean the carburetor
Low speed adjusting screw "too
rich" or "too lean"
Correct setting of low speed
adjusting screw L
Setting of idle speed screw
incorrect – throttle shutter
completely closed
Correct setting of idle speed
screw LA