Sym Joyride125 Service Manual page 66

INSPECTION
CYLINDER HEAD
Check if spark plug and valve holes are cracked.
Measure cylinder head warp with a straightedge
and thickness gauge.
Service limit: 0.5 mm
Valve spring free length
Measure the free length of intake and exhaust
valve springs.
Service limit: 31.5 mm
Valve stem
Check if valve stems are bend, crack or burn.
Check the operation condition of valve stem in
valve guide, and measure & record the valve
stem outer diameter.
Service Limit: IN: 4.90 mm
EX: 4.90 mm
Valve guide
Caution
Before measuring the valve guide, clean
carbon deposits with reamer.
Tool: 5.0 mm valve guide reamer
Measure and record each valve guide inner
diameters.
Service limit: 5.03 mm
The difference that the inner diameter of valve
guide deducts the outer diameter of valve stem
is the clearance between the valve stem and
valve guide.
IN→ → → → 0.08 mm
Service Limit:
EX→ → → → 0.10 mm
6. CYLINDER HEAD/VALVE
To this chapter contents
5.0 mm valve guide reamer
6-7