APRILIA SL 750 SHIVER, Service Station Manual, Page: 178 / 303

Clean off any combustion residues from the
valves.
Check the seat (1) on the valve head with a ruler
flush.
The surface of the seat must not be concave; re-
place the valve if necessary.
Check the clearance between the stem and the
valve guide:
inlet: 0.013 - 0.040 mm (0.00051 - 0.00157 in);
limit: 0.080 mm (0.00315 in)
outlet: 0.025 - 0.052 mm (0.00098 - 0.00205 in);
limit: 0.100 mm (0.00394 in)
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.
Engine
SL 750 SHIVER
ENG - 30