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38. To remove cylinder and piston
(a) Remove the cylinder head
(b) Lift the cylinder off the crankcase and draw it off the piston.
(c) To remove the piston, lake out one gudgeon pin circlip and push out
(he gudgeon pin. If the gudgeon pin is a tight fit in the piston, wrap the
piston in a cloth soaked in hot water After a few minutes the gudgeon
pin will be released and can be pushed out
39. Cylinder maintenance
(a) When the cylinder bore wear has reached the maximum (see Technical
Data) the cylinder should be bored out and an oversize piston and
rings fitted
(b) The cylinder should be rebored and honed to the sizes shown under
Technical Data
40. Piston maintenance (Fig. 7)
Excessive lubricating oil consumption. loss of compression and knocking
are signs that a piston may need attention
(a) If the ring gaps are excessive (see Technical Data) the rings should be
renewed To measure the gaps remove the rings from the piston noting
the order of assembly and which ring face is uppermost
(b) Remove all the carbon deposit from the rings and ring grooves The
small holes (A) in the scraper ring grooves should receive attention as
their purpose is to return excess oil to the sump
(c) Insert the piston into the cylinder bore with the crown towards the
bottom end of the bore to about ½ in (13mm) from the bottom edge
Insert the rings one at a time, pushing each ring hard against the
piston crown to ensure that it is level in the cylinder bore. Withdraw the
piston sufficiently to allow the gap to be checked with a feeler gauge.
(d) Assemble the rings on the piston in the correct order with the correct
face uppermost Rings should not be slack or stuck fast in the groove.
With the piston held in a horizontal position the rings should not fall
downwards unless the piston is shaken.
This applies only to a piston and rings free from grease or oil.
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