TOHATSU BFT 250A, Service Manual

Page: 411 / 639

14-43
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CYLINDER HEAD
Install new valve guides [1] from the valve spring side of
the cylinder head.
Remove new valve guides from the refrigerator one at a
time as you install them, in order to keep them chilled.
Drive each valve guide to the specified height,
measured from the top of the valve guide to the cylinder
head as shown.
After installation, inspect the valve guide for damage.
Replace any damaged valve guide.
For best results, be sure the cylinder head is at room
temperature before reaming valve guides.
Coat the reamer and valve guide with cutting oil.
Rotate the reamer clockwise through the valve guide for
the full length of the reamer.
Continue to rotate the reamer clockwise while removing
it from the valve guide.
• Turn the special tool (valve guide reamer, 5.5 mm)
clockwise, never turn it counterclockwise. Continue
to turn it clockwise as you lift it from the valve guide.
Thoroughly clean the cylinder head to remove any
cutting residue.
Check the valve guide bore; it should be straight, round
and centered in the valve guide, insert the valve and
check operation. If the valve does not operate
smoothly, the guide may have been bent during
installation.
Replace the valve guide if it is bent or damaged.
Check the Valve Stem-to-Valve Guide Clearance (page
14-35).
TOOL:
Valve guide driver, 5.35 x 9.7 mm [2] 07742-0010100
Valve guide extrusion amount:
IN: 21.20 – 22.20 mm (0.835 – 0.874 in)
EX: 20.63 – 21.63 mm (0.812 – 0.852 in)
[2]
[1]
Extrusion amount
VALVE
GUIDE
CYLINDER HEAD
TOOL:
Valve guide reamer, 5.5 mm [1] 07HAH-PJ7A100
[1]
CORRECT INCORRECT