9-6
Rocker Arms and Push Rods
After the heads have been assembled to the crank-
case the push rods and rocker arms can be as-
sembled loosely as shown in Figure 9-4. Oil the
rocker arms and pivots. Insert the push rods into the
hollows in the tappets in the crankcase. Adjust valve
lash.
Breather Valve
The engine breather is located on the Cylinder No.1
head and consists of a leaf valve (Figure 9-5). The
valve maintains a partial vacuum in the crankcase
and provides some separation of crankcase gases
and oil. The crankcase gases are routed to the air
intake for burning in the combustion chambers. Re-
move, clean and examine the parts and replace as
necessary. Re-install the reed valve so that it opens
out. Do not tighten the cover screws to more than
3 lb-ft (4 N-m), or the gaskets may be damaged.
Make sure to reconnect the tube between the
breather outlet and the back of the air filter.
CRANKCASE ASSEMBLY
Disassembly
After removing the engine from the base
(Page 9-3), turn it on its back and remove the main
bearing cover screws. Gently tap the cover with a
soft-faced hammer to loosen it. If the crank and pis-
tons are to come out, remove the cylinder heads
(Page 9-5). Remove the camshaft and tappets
and then the pistons and connecting rods and finally
the crankshaft. Mark each part so that it can be re-
assembled with its mating parts.
Assembly
Before reassembling the crankcase (Figure 9-6),
clean all parts thoroughly and check each against
DIMENSIONS AND CLEARANCES (Page 9-15).
Replace or machine parts as necessary. Replace all
gaskets with new. Liberally oil all rotating and sliding
parts as they are being assembled. Reassemble the
crankcase in the sequence of numbered steps that
follow, beginning on (Page 9-8)
M6 NUT
PIVOT
ROCKER
ARM
PIVOT
BOLT
PUSH
ROD
GUIDE
PLATE
FIGURE 9-4. ROCKER ARMS AND PUSH RODS
BREATHER PLATE
(LEAF VALVE)
COVER
GASKETS
FIGURE 9-5. ENGINE BREATHER VALVE
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