Generac Power Systems TXP - Manual (Page 64)

COMPRESSION 8
CHECKING COMPRESSION
Remove both spark plugs. Insert a compression gauge into one of the
spark plug openings. Crank the engine, using the electric starter.
Repeat test for second cylinder. Maximum pressure differential bet­
ween the two cylinders should not exceed 25 per cent. A greater
pressure differential indicates loss of compression.
Loss of compression is generally caused by any of the following:
1. Defective/leaking cylinder head gasket
2. Sticking/improperly seated valves
3. Worn/broken piston rings or cylinder
REMOVE/INSTALL CYLINDER HEADS
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Remove sheet metal cylinder head
covers and air ducting around the
engine cylinder heads. Note posi­
tions of cylinder head bolts, to
ensure correct reassembly. Longer
bolts are used around the exhaust
valve areas.
To install cylinder heads,.first
install the correct head gasket.
DO NOT USE ANY KIND OF SEALANT ON
HEAD GASKET. Install cylinder head
with bolts in their proper positi­
on. Tighten all head bolts down
evenly by hand. Then tighten bolts
to 160 Inch-Pounds, in the proper
sequence.
IMPORTANT
Wh.e.n removing and installing valves and valve parts, keep all parts
together as a set. Valves,.valve springs and tappets are not inter­
changeable between valve ports.
Issued 3-78 8.1