Dolmar MS-251.4, MS-250.4 Nylon Cutting Head, Operation, Replacing the nylon cord

NYLON CUTTING HEAD

The nylon cutting head is a dual string trimmer head capable of both automatic and bump & feed mechanisms.

The nylon cutting head will automatically feed out the proper length of nylon cord by the changes in centrifugal force caused by increasing or decreasing rpms. However, to cut soft grass more efficiently, bump the nylon cutting head against the ground to feed out extra cord as indicated under operation section.

Operation

–Increase the nylon cutting head speed to approx. 6,000/min.

Low speed (under 4,800/min) is not suitable, the nylon cord will not feed out properly at low speed.

–The most effective cutting area is shown by the shaded area.

If the nylon cord does not feed out automatically proceed as follows:

1.Release the throttle lever to run the engine idle and then squeeze the throttle lever fully. Repeat this procedure until the nylon cord feeds out to the proper length.

2.If the nylon cord is too short to feed out automatically with the above procedure, bump the knob of the nylon cutting head against the ground to feed out the nylon cord.

3.If the nylon cord does not feed out with procedure 2, rewind/replace the nylon cord by following the procedures described under “Replacing the nylon cord”.

Replacing the nylon cord

–First, stop the engine.

–Press on the housing latches inward to lift off the cover, then remove the spool.

–Hook the center of new nylon cord into the notch in the center of the spool, with one end of the cord extending about 80mm (3-1/8") more than the other. Then wind both ends firmly around the spool in the direction of the head rotation (left-hand direction indicated by LH and right-hand direction by RH on the side of the spool).

–Wind all but about 100mm (3-15/16") of the cords, leaving the ends tempo- rarily hooked through a notch on the side of the spool.

–Mount the spool in the housing so that the grooves and protrusions on the spool match up with those in the housing. Keep the side with letters on the spool visible on the top. Now, unhook the ends of the cord from their temporary position and feed the cords through the eyelets to come out of the housing.

Most effective cutting area

Idle speed Full speed

Knob

	Cover
	Latches
Press	Press

Spool80mm(3-1/8”)

For left hand rotation

Spool

100mm(3-15/16”)

Notches

Eyelets

16