Gilera 633721 Workshop Manual page 147

Nexus 500 euro 3
Inspecting the valve sealings
- Insert the valves into the cylinder head.
- Alternatively check the intake and exhaust
valves.
- The test is carried out by filling the manifold with
petrol and checking that the head does not ooze
through the valves when these are just pressed
with the fingers.
- Visually inspect the valve sealing surface.
CAUTION
DO NOT REVERSE THE FITTING POSITIONS OF THE VALVES (RIGHT - LEFT).
- If the sealing surface of the valve is found to be
interrupted at one or more points or is not flat, re-
place the valve.
Inspecting the valve housings
- Clean the valve seats of any carbon residues.
- Using the Prussian blue, check the width of the
impression on the valve seat "V".
- Measure the inside diameter of each valve guide.
- Measure according to the rocking lever thrust di-
rection at three different heights.
Characteristic
Standard value:
1 - 1.3 mm
Admissible limit:
1.6 mm
- If the impression width on the valve seat is larger than the prescribed limits, true the seats with a 45°
mill and then grind.
- In case of excessive wear or damages, replace the head.
Engine
ENG - 147