15
MS 780, MS 880
4.6
Carburetor
Condition
Cause
Remedy
Carburetor floods; engine stalls
Inlet needle not sealing
– foreign matter in valve seat or
cone
Remove and clean the inlet needle,
clean the carburetor
Inlet control lever sticking on
spindle
Check inlet control lever, replace if
necessary
Helical spring not located on nipple
of inlet control lever
Remove the inlet control lever and
refit it correctly
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Fit a new metering diaphragm
Metered diaphragm deformed
Fit a new metering diaphragm
Poor acceleration
Air filter dirty
Clean air filter or replace if
necessary
Setting of low speed screw too lean Check basic carburetor setting,
correct if necessary
Setting of high speed screw too
lean
Check basic carburetor setting,
correct if necessary
Inlet needle sticking to valve seat
Remove inlet needle, clean and
refit
Diaphragm gasket leaking
Fit new diaphragm gasket
Metering diaphragm damaged or
shrunk
Fit a new metering diaphragm
Impulse hose damaged or kinked
Install new impulse hose
Tank vent faulty
Replace tank vent
Leak on fuel hose from tank to
carburetor
Seal connections or install new fuel
hose
