3to 11hp 4-cycle l-head engines - Small Engine Suppliers
3to 11hp 4-cycle l-head engines - Small Engine Suppliers
3to 11hp 4-cycle l-head engines - Small Engine Suppliers
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VALVES<br />
The valves should be checked for proper clearance,<br />
sealing, and wear. Valve condition is critical for proper<br />
engine performance. Valve clearance should be checked<br />
before removal from the engine block if a valve problem<br />
is suspected or when the valves or seats are recut.<br />
Valve clearance (between the valve stem and valve lifter)<br />
should be set or checked when the engine is cold. The<br />
piston should be at T.D.C. on the compression stroke (both<br />
valves closed).<br />
Use a valve grinder or "V" block to hold the valve square<br />
when grinding the valve stem to obtain the proper<br />
clearance (diag. 40).<br />
When servicing the valves, all carbon should be removed<br />
from the valve <strong>head</strong> and stem. If the valves are in a usable<br />
condition, the valve face should be ground using a valve<br />
grinder to a 45 degree angle. If after grinding the valve<br />
face the margin is less than 1/32 of an inch (.793 mm),<br />
the valve should be replaced (diag. 41).<br />
Valves are not identical. Valves marked "EX" or "X" are<br />
installed in the exhaust valve location. Valves marked "I"<br />
are installed in the intake valve location. If the valves are<br />
unmarked, the nonmagnetic valve (<strong>head</strong>) is installed in<br />
the exhaust valve location.<br />
To reinstall the valves, position the valve caps and springs<br />
in the valve compartment. If the spring has dampening<br />
coils, the valve spring should be installed with the<br />
dampening coils away from the valve cap and retainer<br />
(diag. 42).<br />
Install the valves into the guides making sure the correct<br />
valve is in the proper port. The valve stem must pass<br />
through the upper valve cap and spring. Hook the valve<br />
spring retainer on the groove in the valve stem and<br />
release the spring tension to lock the cap in place. Early<br />
models may have a pin through the valve stem. Compress<br />
the spring and cap and use a needle nose pliers to insert<br />
the pin in the valve stem hole. Release the spring and<br />
check that the pin is locked under the cap.<br />
NOTE: If the spring has dampening coils, they always go<br />
toward the stationary surface.<br />
RIGHT<br />
1/32"<br />
(.793 mm)<br />
MINIMUM<br />
DIMENSION<br />
STEM<br />
MARGIN<br />
WRONG<br />
FACE<br />
FACE<br />
45 0<br />
SPRING MUST BE SQUARE<br />
DAMPENING COILS<br />
LOCATED CLOSER<br />
TOGETHER<br />
40<br />
41<br />
42<br />
85
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