Sym MAXSYM 400i Service Manual page 118

Valve spring free length
Measure the free length of intake and exhaust
valve springs.
Service limit:
Inner spring 33.70 mm
Outer spring 38.80 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