Inspection Of Valve - TOHATSU MFS25 Service Manual

10) Inspection of Valve

1. Check valve for dent and wear on the face. Replace if
necessary.
Measure valve stem outer diameter b. Replace if the
2.
diameter is less than specified value.
Valve Stem Outer Diameter b : Standard Value
Intake Side : 5.48 mm ( 0.216 in )
Exhaust Side : 5.46 mm ( 0.215 in )
Functional Limit :
Intake Side : 5.46 mm ( 0.215 in )
Exhaust Side : 5.44 mm ( 0.214 in )
3. Measure valve stem runout. Replace if the runout is over
specified value.
Valve Stem Runout Limit :
Intake Side : 0.07 mm ( 0.0028 in )
Exhaust Side : 0.05 mm ( 0.0020 in )
11) Inspection of Valve Guide
Before inspecting valve guide, check that valve
stem outer diameter is within specified range.
Measure valve guide inner diameter a. Replace cylinder
1.
head if the inner diameter is over specified value.
Valve Guide Inner Diameter a : Standard Value
Intake/Exhaust Side : 5.51 mm ( 0.217 in )
Functional Limit :
Intake Side : 5.55 mm ( 0.0218 in )
Exhaust Side : 5.57 mm ( 0.0219 in )
2. Obtain clearance between valve guide and valve stem by
calculating as described below. Replace cylinder head
and/or valve if the clearance is over specified value.
Clearance between Valve Guide and Valve Stem =
Valve Guide Inner Diameter a – Valve Stem Outer Diameter b :
Intake Side : 0.008 to 0.040 mm ( 0.0003 to 0.0016 in )
Exhaust Side : 0.025 to 0.057 mm ( 0.0010 to 0.0022 in )
Functional Limit :
Intake Side : 0.07 mm ( 0.0028 in )
Exhaust Side : 0.10 mm ( 0.0040 in )
25/30 2006
b
a
b
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