MTD CC4105 User Manual

Page 12

Remove the screw behind the engine cover with a Flat-
head or T-25 Torx screwdriver (Fig. 36).

Screw

Fig. 36

Clean Air Filter

The condition of the air filter is important to the operation of the
unit. A dirty air filter will restrict air flow. This is often mistaken
for an out of adjustment carburetor. Check the condition of the
air filter before adjusting the idle speed screw. Refer to Air
Filter Maintenance.

Adjust Idle Speed Screw

If, after checking the fuel and cleaning the air filter, the engine
still will not idle, adjust the idle speed screw as follows:
1.

Start the engine and let it run at a high idle for a minute to
warm up. Refer to Starting/Stopping Instructions.

Release the throttle trigger and let the engine idle. If the
engine stops, insert a small phillips or flat blade screwdriver
into the hole in the air filter/muffler cover (Fig. 34). Turn the
idle speed screw in, clockwise, 1/8 of a turn at a time (as
needed) until the engine idles smoothly.

NOTE: The cutting attachment should not rotate when the

engine idles.

Fig. 34

Remove

Screws

Engine

Cover

Fig. 35

Muffler

ROCKER ARM CLEARANCE

This requires disassembly of the engine. If you feel unsure or
unqualified to perform this, take the unit to an authorized
service center.
NOTE: Inspect the valve to rocker arm clearance with a feeler

gauge after the first 10 hours of operation and then
every 25 hours of operation thereafter.

• The engine must be cold when checking or adjusting the

valve clearance.

• This task should be performed inside in a clean, dust free

area.

Remove the five (5) screws on back of the engine cover with
a Flat-head or T-20 Torx screwdriver (Fig. 35).

WARNING:

To prevent serious personal injury,

make sure the cutting attachment has stopped
rotating before you turn it off and set it down.

WARNING:

The cutting attachment may spin

during idle speed adjustments. Wear protective
clothing and observe all safety instructions to
prevent serious personal injury.

Idle Ajustment

Screw

MAINTENANCE AND REPAIR INSTRUCTIONS

CARBURETOR ADJUSTMENT

The idle speed of the engine is adjustable. An idle adjustment
screw is reached though a hole in the top of the engine cover
(Fig. 34).
NOTE: Careless adjustments can seriously damage your unit.

An authorized service dealer should make carburetor
adjustments.

Check Fuel

Old fuel is usually the reason for improper unit performance.
Drain and refill the tank with fresh fuel prior to making any
adjustments. Refer to Oil and Fuel Information.

If the cutting attachment rotates when the engine idles, turn
the idle speed screw counterclockwise 1/8 of a turn at a time
(as needed), to reduce idle speed.

Checking the fuel, cleaning the air filter, and adjusting the idle
speed should solve most engine problems. If not and all of the
following are true:
• the engine will not idle
• the engine hesitates or stalls on acceleration
• there is a loss of engine power
Have the carburetor adjusted by an authorized service dealer.