MTD 18HP service manual High Speed Tracking Adjustment, Enginge RPM Check and Adjustment

Performance Adjustments

A. High Speed Tracking Adjustment

If mower tracks to one side with both lap bars in fully forward position:

1.Check air pressure in all four tires:

a.Pressure should be within specified ranges and balanced side-to-side.

b.Rear tires 8-10 psi. recommended (20 psi MAX.)

c.Front tires 20-25 psi. recommended (40 psi MAX.

2.Check hydraulic fluid level (Ref. Engine owner’s manual)

3.Verify that the mower does not creep when the engine is running, the lap bars are in the neutral position and the parking brake is released. (Refer to section D-3 on page 19 of this manual if this condition exists).

4.Recheck the tracking after any adjustments based on the above.

5.If uneven tracking persists, adjust as follows. (see Fig. 10)

a.Unit tracks to the RIGHT, adjust Left lap bar stop bolt to make it longer.

b.Unit tracks to the LEFT, adjust Right lap bar stop bolt to make it longer.

6.Re-check the tracking and make any fine tun- ing adjustments to the lap bar stop bolts as required.

Note: If stop bolt is adjusted too far, track-

ing problem will change sides. Make the fine tuning adjustments by shortening the same bolt.

Figure. 10

Lap Bar Stop Bolt

B. Enginge RPM Check and Adjustment

Description	High RPM Spec.	Low RPM Spec.
--	--	--
--	--	--
18 HP Briggs	3600 +/-50	1650 +/-100

NOTE: RPM Specs. are for free running engines under no load.

1.Verify that the lap bars are in the neutral posi- tion, the parking brake is on, and the PTO drive is disengaged.

2.Start the mower and let it run at approximately half throttle for 3-5 minutes to bring the engine up to operating temperature.

3.Locate the Hour Meter/Tachometer/ Service Minder display on the right hand operator con- trol panel. (see Fig.1 on page 8 of the manual) This display defaults to Tachometer mode when engine is running.

4.Move the throttle lever to the high speed posi- tion and note the RPM reading on the display.

5.Move the throttle lever back to the low speed position and again note the displayed RPM’s.

6.Compare these noted RPM readings to the specifications in Table 1, for the engine that is on your mower.

7.If the readings do not correspond to the ranges in the table, refer to the engine owner’s manual for the proper adjustment procedures.

8.If adjustments per the engine operator’s man- ual do not result in proper RPM readings, con- tact your service technician.

9.Note: The throttle cable sheath may shrink or slip over time, changing the relationship between the throttle lever on the left hand operator control panel and the throttle arm on the engine. To readjust the throttle cable:

a.Make sure the engine is off, place lap bars in the neutral position, set the parking brake, and disconnect and ground both of the spark plug wires.

b.Locate and loosen the cable clamp on the engine throttle plate.

c.Place the operator’s throttle lever to the high speed position and then slide the cable through the clamp until the throttle arm is in the full throttle position. (Ref. Engine owner’s manual)

d.Tighten the cable clamp.

e.Move the operator’s throttle lever between high and low speed and verify that the engine throttle arm also moves through it’s full range of motion.

f.Repeat as required to obtain proper throt- tle adjustment.

24