Stihl KM 85 - Engine; Carburetor

12 FC 75, FC 85, FH 75, FS 75, FS 80, FS 85, HL 75, KM 85, KW 85
4.4 Engine
Always check and, if necessary,
repair the following parts before
looking for faults on the engine:
– Air filter
– Fuel system
–Carburetor
– Ignition system
1)
Condition Cause Remedy
Engine does not start easily, stalls
at idle speed, but operates normally
at full throttle
Oil seals in crankcase faulty Install new oil seals
1)
Crankcase leaking / damaged
(cracks)
Seal / replace the crankcase
1)
Muffler leaking Seal / replace the muffler
Engine does not deliver full power
or runs erratically
Piston rings worn or broken Install new piston rings
1)
Muffler / spark arresting screen
carbonized
Clean muffler (inlet and
exhaust openings), replace
spark arresting screen
Air filter element dirty Fit new air filter element
Fuel / impulse line kinked or
cracked
Fit new lines or position
without kinks
Engine overheating Insufficient cylinder cooling.
Air inlets in fan housing
blocked or cooling fins on
cylinder very dirty
Thoroughly clean all cooling air
passages and cooling fins
1)
see "Series 4137 Powerhead" service manual“