Remove Crankshaft and Camshaft
1. Remove spark plug wire from the spark plug and then
remove the spark plug.
2. Drain oil from engine and all fuel from fuel tank.
3. Remove blower housing/rewind assembly as instructed
in
Adjust Armature Air Gap
found in Section 2.
4. Remove flywheel/fan assembly as instructed in
Remove
Flywheel
found in Section 9.
5. Remove burrs and clean crankshaft (J), then remove
crankcase cover (D) and gasket (C).
Note:
To ease crankcase cover removal, position piston at
TDC with both valves closed.
Note:
If crankcase cover sticks, tap lightly with soft hammer
on alternate sides near dowel pins (B). It is not necessary
to remove dowel pins.
6. Carefully tip engine with PTO end facing up, as shown
in illustration.
7. Rotate crankshaft until timing marks (H) are aligned.
With camshaft in this position, the valve tappets (U) will
remain clear of cam lobes. Lift out camshaft (K).
8. Remove one tappet and mark it for reinstallation. Each
tappet must be installed into the same hole as removed
from. Follow the same procedure for the second tappet.
9. Remove rocker cover and cylinder head as instructed
in
Remove Cylinder Head
found in Section 7.
10. Remove connecting rod cap and piston as instructed
in
Remove Piston and Connecting Rod
in Section 8.
11. Slide crankshaft out from cylinder housing (A).
Inspect Crankshaft and Camshaft
Inspect Crankshaft
1. Inspect crankshaft (J) for scoring on PTO journal (M),
crankpin journal (N), and MAG journal (P). Replace
crankshaft if scoring is found or if crankshaft is bent.
DO NOT attempt to straighten bent crankshafts.
2. Using a micrometer, measure the journal diameters.
Compare results to values listed in
Section 13 - Engine
Specifications
. If wear exceeds the reject dimensions,
replace the crankshaft.
Inspect Camshaft
1. Check gear (R) for worn or damaged teeth. Check lobes
(S) and journals (Q, T) for scratching or scoring. Check
compression release mechanism (located under gear
(R)) for wear, burrs, or sticking. Replace camshaft if
any of these conditions are found.
2. Using a micrometer, measure the journal diameters.
Compare results to values listed in
Section 13 - Engine
Specifications
. If wear exceeds the reject dimensions,
replace the camshaft.
Install Crankshaft and Camshaft
1. Lubricate the cylinder housing oil seal with engine oil.
2. Make sure the paddle (G) on the governor shaft is
positioned on top of the governor cup and washer (F)
inside the cylinder housing (A).
3. Support both ends of the crankshaft (J), and carefully
install into the cylinder housing.
4. Install piston and connecting rod cap as instructed in
Install Piston and Connecting Rod
found in Section 8.
5. Apply lubricant to shafts of tappets (U). Install each
tappet into the same hole that it was removed from.
6. Install camshaft, making sure tappets clear cam lobes.
Timing marks (H) must align as shown.
Install Crankcase Cover
1. Install dowel pins (B) in dowel pin holes of cylinder
housing (A).
2. Using a new gasket (C) and an oil seal protector, install
crankcase cover (D). Do not force cover on cylinder
housing.
3. Install screws (E). Step-torque screws in the sequence
shown until final torque value is achieved. Refer to the
illustration at the beginning of this section for the proper
sequence. Torque screws to value listed in
Section 13
- Engine Specifications
.
NOTICE
Do not fully torque each screw in one step as
it may result in a warped crankcase cover. Step-torque
all screws to approximately 1/3 of final torque value, then
to 2/3 final torque value, then finish at final torque value.
4. Install valves, springs and seals as instructed in
Assemble Cylinder Head
found in Section 7.
5. Install cylinder head as instructed in
Install Cylinder
Head
found in Section 7.
6. Reinstall push rods and rocker arms. Adjust valve
clearance as instructed in
Adjust Valve Clearance
found
in Section 2.
7. Install rocker cover with a new rocker cover gasket.
Torque screws to value listed in
Section 13 - Engine
Specifications
.
8. Install flywheel/fan assembly as instructed in
Install
Flywheel
found in Section 9.
9. Install blower housing/rewind assembly as instructed
in
Adjust Armature Air Gap
found in Section 2.
10. Fill engine with oil. Refer to
Change Oil
found in Section
2.
69
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