Emissions Carburetor Idle Mixture Adjustment Procedures - Tecumseh TC 200 Technician's Handbook

8. Install the pump gasket over the locator pins on the
pump cover, add the pump diaphragm next, and
place the assembly on the carburetor body. Check
to see that the locator pins fit the corresponding holes
in the carburetor body. Install the pump cover
retaining screw (diag. 3-13).
9. If removed on Walbro carburetors, install a new fuel inlet
fitting in the same position as the original (diag. 3-14).
When installing a new fitting, insert the tip into
the carburetor body, then coat the exposed portion of
the shank with Loctite grade A (red), then press it in
squarely using support on the opposite side to
prevent damage to the carburetor body or fitting.
Press it in until the fitting bottoms out in the carburetor
body.
10. Install the choke and throttle shaft assemblies in the
reverse order of removal. Visually check for proper
operation of the choke and throttle.
NOTE: Do not re-use old choke or throttle plate shutter screws. New screws are treated with a dry Loctite adhesive to
secure them in place.
11. If applicable, attach the air vane and torque the mounting screw to 3-5 inch pounds (.34 - .57 Nm) (diag. 3-14).
12. Newer style TC series engines use an insulator / spacer between the carburetor and cylinder. That spacer MUST be
installed, as shown, for the fuel pump to operate.
EMISSIONIZED TC CARBURETOR
The Tillotson carburetor is now an emissions grade carb. It has a married idle and high speed circuitry with limited jet
adjustments on the idle.
EMISSIONS CARBURETOR IDLE MIXTURE
ADJUSTMENT PROCEDURES
The carburetor is preset at the factory at a normal setting
required for initial engine operation.
Allow the engine to reach normal operating temperature
(after 3-5 minutes).
Set the engine speed control in the idle position. With the
engine at idle speed (Note: must be less than 2400 R.P.M.
for accurate adjustment). Using a small tip screw driver that
fits through the access hole in the limiter cap, adjust the
mixture screw slowly clockwise until the engine R.P.M.
just starts to decrease. Stop and note this screw position.
Turn the idle mixture screw slowly counterclockwise. As the
engine increases R.P.M. continue to slowly turn the
screw counterclockwise until the engine R.P.M. starts to
decrease. Note this position and turn the mixture screw back
clockwise halfway between the two engine R.P.M.
drop off positions.
Verify the engine will accelerate from low speed to high speed
and that the idle speed remains at the desired
setting.
Once adjustments are complete, center the adjustment
limiter cap between the two stops and press inward to
engage the limiter. The limiter will snap into position and
engage the adjusting screw. All future adjustments should
now be made using the adjusting slot in the limiter cap.
CAUTION: Once the limiter cap is snapped into place it is not
possible to remove the limiter or to adjust the mixture screw
beyond the limits of the limiter assembly. Make sure
that initial adjustments are made per the above procedure
prior to engaging the limiter cap.
THROUGH HOLE
TOWARD SPARK
PLUG
VACUUM CHANNEL
TOWARDS CYLINDER
3-14
3-15
15