Sym GTS 250 Service Manual page 78

Remove valve cotters, spring retainers, springs
and valves.
Remove valve stem seals.
Clean carbon deposits in combustion chamber.
Clean residues and foreign materials on cylinder
head matching surface.
Caution
Do not damage the matching surface of cylinder
head.
To this chapter contents
6. Cylinder Head / Valve
Inlet valve
Inner spring
Exhaust valve
Outer spring
Spring retainer
Cotter
Valve stem seals
6-7