Briggs & Stratton 700 DOV Series, Руководство по ремонту

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6
6
Before the cylinder head can be removed, other
external parts must be removed, such as the air
cleaner, fuel tank, oil fill tube, blower housing,
muffler, carburetor, control bracket assembly,
and intake manifold.
Remove Cylinder Head
1. Remove spark plug.
2. Remove four screws ( A , Figure 6-1) from
valve cover then remove cover ( B ) and
gasket ( C ). Discard gasket.
3. Remove cylinder head screws ( D ), then
remove head ( E ) and gasket ( F ) from
cylinder. Discard gasket.
Disassemble
1. Remove the retaining pin and the intake
and exhaust levers ( G ).
2. Place a clean shop rag ( L ) under the
cylinder head to hold valves in place while
compressing spring.
3. Using thumb pressure, compress valve
spring retainer until larger hole ( H ) of
retainer fits over valve stem.
4. Remove retainer, spring, valve, and valve
seal ( J ).
5. Repeat for other valve.
6. Using a plastic scraping tool, carefully
clean all traces of head gasket from the
head and cylinder mating surfaces.
Inspection
1. Visually inspect cylinder head for cracks,
excessive heat discoloration, warping, and
burned or damaged valve seats. Replace
head, if any of these problems are found.
2. Inspect valves for wear or damage.
Replace if necessary.
3. Oil the intake valve stem then insert valve
into head.
4. Using Valve Lapping Tool #19258 and
Lapping Compound #94150, lap valve and
seat together to assure a good sealing
surface. Remove valve, then repeat
procedure for the exhaust valve.
5. Thoroughly clean both valves and valve
seats of all lapping compound residue.
Assemble
1. Lightly coat valve stems with Valve Guide
Lubricant #93963, then insert valves into
cylinder head. Do not get lubricant on
valve face, valve seat, or exposed end of
valve stem.
2. Oil inside diameter of new stem seal and
install on intake valve stem. Slide seal
down against the cylinder head.
3. Support valve side of cylinder head on
clean shop rags. Place valve springs and
valve spring retainers over valve stems.
Using thumbs, press against each retainer
until it securely locks into groove in valve
stem.
Install Cylinder Head
1. Using new head gasket, install cylinder
head on cylinder and start screws by
hand.
2. Step-torque screws in sequence shown
( K ) to values listed in Section 12 - Engine
Specifications.
3. Install intake and exhaust levers with
retaining pin.
4. Rotate crankshaft at least twice to ensure
proper movement of the levers and valves.
5. Adjust valve clearance per Section 1, then
install a new valve cover gasket and the
valve cover. Torque screws to values
listed in Section 12 - Engine
Specifications.