PIAGGIO MP3 400 i.e. - Inspecting the Valve Housings; Inspecting the Valves; Standard Diameter

- 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.
- 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.
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".
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.
Inspecting the valves
- Measure the diameter of the valve stems in the three positions indicated in the diagram.
STANDARD DIAMETER
Specification Desc./Quantity
Inlet: 4.987 - 4.972 mm
Outlet: 4.975 - 4.960 mm
MP3 400 i.e. Engine
ENG - 63