Sym GTS 250 Service Manual page 80

Valve spring free length
Measure the free length of intake and exhaust
valve springs.
Service limit:
Inner spring 35.20 mm
Outer spring 36.90 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.
Service Limit: IN¡ ÷ 0.08 mm
EX¡ ÷ 0.10 mm
Caution
If clearance between valve stem and valve guide
exceeded service limit, check whether the new
clearance that only replaces new valve guide is
within service limit or not. If so, replace valve
guide.
Correct it with reamer after replacement.
If clearance still exceeds service limit after
replaced valve guide, replace valve stem too.
Caution
It has to correct valve seat when replacing valve
guide.
To this chapter contents
6. Cylinder Head / Valve
5.0 mm valve guide reamer
6-9