EMAK K 700 H Workshop Manual page 46

Exhaust valve guide reaming
For best results, be sure the cylinder head is at room temperature
before reaming the exhaust valve guide.
1. Coat the reamer and valve guide with cutting oil.
2. Rotate the reamer clockwise through the valve guide the full
length of the reamer.
3. Continue to rotate the reamer clockwise while removing it from
the valve guide.
4. Thoroughly clean the cylinder head to remove any cutting
residue.
5. Check the valve guide bore; it should be straight, round and
centred 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.
6. Check the valve stem-to-guide clearance.
Valve seat reconditioning
1. Thoroughly clean the combustion chambers and valve seats to
remove carbon deposits.
2. Apply a light coat of Prussian Blue or erasable felt-tipped marker
ink to the valve faces.
3. Insert the valve, and then lift them and snap them closed against
their seats several times. Be sure the valve does not rotate on the
seat. The transferred marking compound will show any area of
the seat that is not concentric.
4. Using a 45° cutter, remove enough material to produce a smooth
and concentric seat. Follow the valve seat cutter manufacturer's
instructions.
Turn the cutter clockwise, never counter clockwise.
Continue to turn the cutter as you lift it from the valve seat.
5. Using the 30°~32° and 60° cutter to narrow and adjust the valve
seat so that it contacts the middle of the valve face. The
30° ~ 32° cutter removes material from the top edge. The 60°
cutter removes material from the bottom edge. Be sure that the
width of the finished valve seat is within specification.
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Workshop manual