Gilera Nordwest, Workshop Manual

Page: 58 / 136

DISASSEMBLY
Remove the head group, gasket and rubber anti-vibration devises, as de-
scribed in section 7.
Remove the water pump, found on the left of the cylinder (fig. 1).
Remove the thermostat’s housing on the front of the cylinder (fig. 2).
Lift the cylinder by hand. If necessary, use a plastic or rubber mallet to break
the seal (fig. 3).
After having removed the cylinder, cover the opening of the crankcase with pa-
per or clean cloth, then remove the gudgeon pin lockring (fig. 4) and slide out
pin using special tool 19.1.20530 as a punch.
If necessary use a mallet (remember to support the piston on the other side)
(fig. 5).
Remove the base gasket of the cylinder and the rubber O-ring, found around
the oil feed line (fig. 6).
INSPECTION
After a thorough cleaning of all parts, all components must go through a
careful visual inspection. Replace all parts that show sign of damage and/or
wear. Careful attention goes to cylinder wall, piston surfaces, rings and
gudgeon pin, with no signs of scoring, deep grooves, shrinkage or any other
damage.
Cylinder
Measure bore diameter (with a micrometer) at three different heights and at
90° to one another (one measurement must be parallel to the gudgeon pin) in
order to see excessive ovalisation and taper. If excessive wear is noted, both
cylinder and piston must be replaced (fig. 7).
Max. taper = 0.02 mm
Max. ovalisation = 0.01 mm
Piston
Piston diameter is measured at 90° to the gudgeon pin and again at 12 mm
(350cc) and 7 mm (500cc) from the base of the skirt, using a micrometer
(fig. 8).
Min. clearance (service limit) = 0.1 mm
8 - 2,1