Stihl MS 201 Manual page 17

Condition
Engine speed drops quickly under
load – low power
Engine running extremely rich, has
no power and a very low maximum
speed
16
Cause
Air filter dirty
Throttle shutter not opened fully
Tank vent faulty
Fuel pickup body dirty
Fuel strainer dirty
Leak in fuel hose from tank to
carburetor
Setting of high speed screw (H) too
rich
Main jet bores or ports blocked
Pump diaphragm damaged or
fatigued
Ignition timing wrong, flywheel out
of adjustment
– key in flywheel has sheared off
Choke shutter does not open
Remedy
Clean air filter or replace if
necessary
Check throttle rod
Fit new tank vent
Fit new pickup body
Clean fuel strainer in carburetor,
replace if necessary
Seal connections or install new fuel
hose
Check basic setting, correct if
necessary
Clean the carburetor
Fit new pump diaphragm
Install new flywheel
Check carburetor and choke shaft,
service or replace if necessary
MS 201, MS 201 C, MS 201 T, MS 201 TC