Parts Inspection And Measurement - Takeuchi TB 175 Handbuch

4. Disassembly, inspection and reassembly of engines

4.2.5 Parts Inspection and measurement

(1) Cylinder head
Clean the cylinder head, mainly the combustion surface,
valve seats and intake/exhaust ports, remove carbon
deposit and bonding agent, and check the surface state.
(a)Appearance check
Check mainly discoloration and crack. If crack is
suspected, perform color check.
(b)Combustion surface distortion
Apply a strait-edge in two diagonal directions and on
four sides of the cylinder head, and measure distortion
with a thickness gage.
Standard
Distortion 0.05 or less
Valve sink
(c)
Measure with the valve inserted to the cylinder head.
Intake
3TNV82A
(2-valve head)
Exhaust 0.30 to 0.50
4TNV84 Intake
3TNV84 (T)
3/4TNV88
Exhaust 0.30 to 0.50
(2-valve head)
4TNV84T Intake
4TNV94/98 (T)
Exhaust 0.35 to 0.55
(4-valve head)
Intake
4TNV106 (T)
(4-valve head)
Exhaust
(d)Seat contact
Apply a thin coat of minimum on the valve seat. Insert
the valve in the cylinder and push it against the seat to
check seat contact.
Standard: Continuous contact all around
mm
Limit
0.15
Standard Limit
0.35 to 0.55 0.8
0.8
0.30 to 0.50 0.8
0.8
0.36 to 0.56 0.8
0.8
0.5 to 0.7 1.0
0.7 to 0.9 1.2
Straight-edge
Thickness gage
Distortion at combustion surface
Depth micrometer
mm
Valve seat contact
76
Valve sink
Valve sinking depth
Valve sink depth
Seat