Sym PA12B User Manual

7. Cylinder Head / Valve
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Valve Stem Inspection
7-9
Check if valve stem is bent, cracked or burnt.
Check the operation condition of valve stem in
valve guide, and measure the valve stem
outer diameter.
Service Limit:
Intake valve: Under 5.42mm
Exhaust valve: Under 5.40mm
Valve Guide Inspection
Caution
z Clear all the carbon deposit with reamer
before measuring the valve guides.
Special tool: Valve Guide Reamer 5.0mm
Measure and record each valve guide inner
diameters.
Service Limit：5.50mm
The difference that the inner diameter of valve
guide deducts the outer diameter of valve
stem is the clearance value between the valve
stem and valve guide.
Service Limit：
Intake: Over 0.08mm
Exhaust: Over 0.10mm
Caution
z If clearance is over service limit, check if
only replaces new valve guide will fix the
clearance into service limit or not. If yes,
replace valve guide only.
Fix the guides with reamer after replacement.
If clearance still exceeds service limit after
replacing valve guides, please also replace
valve stem too.
Caution
z Fix the valve seat when replacing valve
guides.
Valve Guide Reamer 5.0mm
Valve Guide Reamer 5.0mm

Sym PA12B Specifications

General

Brand	Sym
Model	PA12B
Category	Motorcycle
Language	English