9
1
Tecumseh 2 Cycle Diaphragm Adjustments
NOTE: For meeting emission requirements, some
carburetors have fixed-main or idle jets. The
absence of the adjustment screw indicates fixed
jets and no adjustment is necessary.
Diaphragm-Dual Adjustment.
Turn mixture adjusting screws in finger tight to the
closed position, then one (1) turn out from closed
position. Thissettingisapproximate. Thiswillallow
theenginetobestartedsothecarburetorcanbefine
tuned.
Starttheengineandletitwarmupforapproximately
3-5 minutes. Do not adjust the carburetor when
the engine is cold.
Set the throttle control to idle. If it is a fixed speed
type, manually hold the throttle against the idle
speed adjustment screw.
The throttle lever must be held against the crack screw for low speed adjustments or all adjustments will
be incorrect and cause poor performance and unsatisfactory operation.
With the engine idling and throttle lever against the idle speed regulating screw, turn the low speed
adjustment screw slowly clockwise from the NORMAL setting until the engine falters. Remember this
location. TurnthescrewcounterclockwiseuntilenginejuststartstosputterordropsinR.P.M.. Remember
this location. Turn the screw clockwise until it is halfway between your first position where the engine
falteredandyourlastpositionwheretheenginestartedtosputter. Thiswillbetheoptimumlowspeedsetting
on your carburetor.
Nextrun theengine atgoverned speed. Thehigh speedadjustments aremade basicallythe same as the
low speed adjustments, with the exception of the settings being made 1/8 of a turn at a time, from the
NORMAL settings. NOTE: It may be necessary to re-check the idle mixture adjustment after performing
the high speed adjustment.
Diaphragm-Single Adjustment.
Turnthemixture adjustmentscrewfinger tight totheclosed position,thenone (1) turnoutfrom theclosed
position. This setting is approximate and will allow the engine to be started so the carburetor can be fine-
tuned.
Start the engine and let it warm up for approximately 3-5 minutes. Do not adjust the carburetor when the
engine is cold.
Set the throttle control to idle. If it is a fixed speed type, manually hold the throttle against the idle speed
adjustment screw.
NOTE: Iftheenginefaltersorstopsafterthechokeleverismovedtothe"OFF"position,openthemixture
adjusting screw 1/4 turn (counterclockwise) and restart the engine.
Withtheenginerunning,placethespeedcontrolinthe"slow"positiontomakemixtureadjustments. Turn
the mixture screw slowly clockwise from the NORMAL setting until the engine falters. Remember this
location. Turnthescrew counterclockwise until theenginejuststartstosputterordropsinR.P.M. Remember
this location. Turn the screw clockwise until it is halfway between your first position where the engine
falteredandyourlastpositionwheretheenginestartedtosputter. Thiswillbetheoptimumsettingonyour
carburetor.
IDLE MIXTURE
SCREW MAIN MIXTURE
SCREW
NOTE: If no tension
spring is present, it
may be a fixed jet.
