Section 01 ENGINE MEASUREMENT
Subsection 01 (MEASUREMENT PROCEDURES)
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1. Combustion chamber
NOTE:
When checking the combustion chamber
volume, engine must be cold, piston must be free
of carbon deposit and cylinder head must be lev-
eled.
– Remove both spark plugs and bring one piston
to Top Dead Center using a TDC gauge.
– Obtain a graduated burette (capacity 0 - 50 cc)
and fill with an equal part (50/50) of gasoline and
injection oil.
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1. Graduated burette (0 - 50 cc)
– Open burette valve to fill its tip. Add liquid in
burette until level reaches 0 cc.
– Inject the burette content through one spark
plug hole until liquid touches the top hole.
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TYPICAL
1. Top of spark plug hole
NOTE:
The liquid level in cylinder must not drop
for a few seconds after filling. If so, there is a
leak between piston and cylinder. The recorded
volume would be false.
– Let burette stand upward for about 10 minutes,
until liquid level is stabilized.
– Read the burette scale to obtain the quantity of
liquid injected in the combustion chamber.
The volume should be within the allowable range.
Refer to TOP END section of the appropriate en-
gine for the specifications.
If the volume of the combustion chamber is not
within specifications, change cylinder base gasket
thickness as follow.
A higher volume dictates a thinner gasket.
A lower volume dictates a thicker gasket.
– Repeat the procedure for the other cylinder.
PISTON/CYLINDER WALL
CLEARANCE
Method with a Used Piston
Using a micrometer, measure piston skirt perpen-
dicularly (90°) to piston pin and at the specified dis-
tance as per following table.
ENGINE
MAXIMUM “A” mm (in)
717
29 (1.142)
787 RFI
28 (1.102)
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smr2005-085
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