Carburetor - Stihl MS 650 Manual

4.5

Carburetor

Condition
Carburetor floods;
engine stalls
Poor acceleration
14
Cause
Inlet needle not sealing. Foreign
matter in valve seat or cone
damaged
Inlet control lever sticking on
spindle
Helical spring not located on nipple
of inlet control lever
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Inlet control lever too high
(relative to correct installed
position)
Idle jet too lean
Main jet too lean
Inlet control lever too low
(relative to correct installed
position)
Inlet needle sticking to valve seat
Diaphragm gasket leaking
Metering diaphragm damaged or
shrunk
Impulse hose damaged or kinked
Remedy
Remove and clean or replace the
inlet needle, clean the fuel tank,
pickup body and fuel line if
necessary
Free off the inlet control lever
Remove the inlet control lever and
install it correctly
Fit a new metering diaphragm
Replace inlet control system (lever,
spindle, spring)
Rotate low speed screw (L)
counterclockwise (richer), (no
further than stop on carburetors
with limiter caps)
Rotate high speed screw (H)
counterclockwise (richer), (no
further than stop on carburetors
with limiter caps)
Install new inlet control system
(lever, spindle, spring)
Remove inlet needle, clean and
refit
Fit new diaphragm gasket
Fit new metering diaphragm
Fit new impulse hose
MS 650, MS 660