Page 1403 - Workshop Manual - Tunland (2017)

ENGINE MECHANICAL - CYLINDER HEAD,VALVE 15-67

(a) Before finishing the valve seat, check the clearance between the valve guide and the
valve rod. Finish it after replacement if necessary.

(b) Finish the width and angle of the valve seat
to the rated values with a grinder. If the valve
contact position is too high, that is, the valve
face indentation is above average in the range
of the valve face, corrected the valve seat
with 30 degrees and 45 degrees reamer. 15

3 . If the valve contact position is too low, that
is, the valve face indentation is below
average in the range of the valve face,
corrected the valve seat with 60 degrees
and 45 degrees reamer.
• The valve face indentation is the actual
contact area of valve seat 1 and valve
2.
• Grind the joint plane of the valve and
valve seat with the valve running in.
• Clean the valve and valve seat ring
after running in.

(d) Once finished, polish the valve and the valve seat together with abrasive.Then measure
the protruded height of the valve rod.

12 . Replace the valve seat:
(a) Cut part of the valve seat to replace from
inside and remove it.
(b) Finish the valve seat hole on the cylinder head
subject to the outer diameter of the larger
valve seat.
Inner diameter of valve seat insert hole of
cylinder head

Standard value of inside diameter (exhaust
valve) of cylinder cap insert ring:0.922～
30.948mm
Standard value of inside diameter (intake
valve) of cylinder cap insert ring:33.485～
33.485mm

(c) Before installing the valve seat, heat the
cylinder head to 250℃, or chill the seat in