Troy-Bilt TB4000 manual Carburetor Adjustment, Rocker ARM Clearance, Check Fuel

Maintenance (continued)

Idle

Adjustment

Screw

Fig. 6-15

CARBURETOR ADJUSTMENT

The idle speed of the engine is adjustable the screw next to the air filter cover (Fig 6-15).

NOTE: Careless adjustments can seriously damage your unit. An authorized service dealer should make carburetor adjustments.

Check Fuel

Old fuel is usually the main reason for the unit not running properly. Drain and refill the tank with clean, fresh unleaded fuel prior to doing any adjustments. See

Section 4, Oil and Fuel, Recommended Fuel.

Clean Air Filter

The condition of the air filter is important to the opera- tion of the unit. A dirty air filter will restrict air flow and change the air/fuel mixture. This is often mistaken for an out of adjustment carburetor. Check the condition of the air filter before adjusting the idle speed screw. See Section 6, Maintenance, Air Filter Maintenance.

Adjust Idle Speed Screw

The cutting attachment may be spinning during idle speed adjustment. Wear protective clothing and observe all safety instructions to prevent serious personal injury.

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.

2.Release the throttle trigger and let the engine idle. If the engine stops, insert a small phillips or flat blade screwdriver into the screw next to the air filter cover (Fig. 6-15). 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.

3.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 mixture, cleaning the air filter, and adjusting the idle speed screw should solve most engine problems.

If not and:

•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.

When the unit is turned off make sure the cutting attachment has stopped before the unit is set down to prevent serious personal injury.

ROCKER ARM CLEARANCE

NOTE: This requires some disassembly of the engine. If you feel unsure or unqualified to perform this, take the unit to an authorized service center.

Inspect the valve to rocker arm clearance every 50 hours of operation using a flat feeler gauge.

NOTE: The engine must be cold when checking or adjusting the valve clearance.

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

1.Loosen the four (4) screws shown in figure 6-16.

2.Remove the three (3) screws that secure the engine cover (Figs. 6-16 and 6-17).

3.Disconnect the spark plug wire.

4.Remove the spark plug

5.Remove the engine cover (Fig. 6-16).

6.Remove the screw holding the rocker arm cover with a large flat blade screwdriver or Torx T25 bit (Fig. 6-18). Remove the rocker arm cover, and gasket.

7.Pull the starter rope slowly to bring the piston to Top Dead Center.

•While looking in the spark plug hole (Fig. 6-18), the piston is at the top of the stroke.

•Both valves are closed.

•Both rocker arms move freely.

If not, repeat this step.

8.Slide the feeler gauge between the rocker arm and the valve return spring. Measure the clearance between the valve stem and rocker arm (Fig 6-19). Do both intake and exhaust valves.

The recommended clearance for both intake and exhaust is .003–.006 inch (.076–.0152 mm). The feeler gauge should slide between the rocker arm and valve stem with a slight amount of resistance, without binding.

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