APRILIA SHIVER 900, Service Station Manual

Page: 242 / 444

Check the valve eccentricity:
valve stem (3) maximum eccentricity allowed:
0.05 mm (0.00197 in)
valve head (4) maximum eccentricity allowed:
0.05 mm (0.00197 in)
Check that the fixing grooves (5) of the valve cot-
ters are in proper conditions.
VALVE SPRINGS
Carry out a measurement and a visual inspection
of the valve springs for damage, distortion or loss
of tension.
Measure the spring length at release position.
Valve springs: minimum wear limit (6) 42.5 mm
(1.673 in).
Valve springs: minimum wear limit (7) 38 mm
(1.496 in).
Checking the cylinder head
•
Using a round scraper, clean off any carbon deposits in the combustion chamber.
CAUTION
DO NOT USE A POINTED INSTRUMENT TO AVOID DAMAGING OR SCRATCHING THE SPARK
PLUG THREADS OR THE VALVE SEATS.
•
Check the head for damage or scratches and replace it if necessary.
•
Check there are no mineral deposits or rust in the head water cooled jacket; clean off if
required.
•
Use a checking ruler and a thickness gauge positioned diagonally to the ruler to measure
the cylinder head distortion.
Maximum cylinder head distortion: 0.03 mm (0.0012 in)
•
Check that the tappet covers and the camshaft toothed wheel cover are not damaged or
worn; replace the defective part(s).
Installing the overhead camshaft
The camshaft refitting procedure is described in the "Timing" section.
See also
Timing
Engine
SHIVER 900
ENG - 242