Honda CR250R 2004 Owner's Manual page 34

Remove the cylinder by removing the four flange nuts.
Remove the gasket and dowel pins.
Inspect and clean the exhaust valves and linkage, as
necessary (page 27).
CAUTION:
•
Do not pry on or strike the cylinder.
Place a clean shop towel into the crankcase to keep
debris out. Remove the reed valve from the cylinder by
removing the six carburetor insulator mounting bolts.
Replace the gasket.
(1) CYLINDER (2) CYLINDER FLANGE NUTS
(3) REED VALVE
Piston Removal
Remove the piston pin clips using a pair of needle-nose
pliers. Press the piston pin out of the piston, and
remove the piston.
CAUTION:
•
Do not damage the piston.
•
Always support the piston when pressing out the
pin.
•
Do not let the clips fall into the crankcase.
NOTE:
•
Under racing conditions, the piston and rings should
be replaced after 7.5 hours of running. Replace the
piston pin and connecting rod small end bearing
after 22.5 hours of running.
(1) PISTON (2) PISTON RINGS (3) PISTON PIN
(4) PISTON PIN CLIP
Spread each piston ring and remove by lifting it up at
a point just opposite the gap.
CAUTION:
•
Do not damage the piston rings by spreading the
ends too far.
Piston Inspection
We recommend you consult the Service Manual or
your authorized Honda dealer for correct service limit
measurements.
Piston/Cylinder Head Decarbonizing
Remove the carbon deposits from the cylinder head
and piston dome.
CAUTION:
•
Use care not to scratch the cylinder head and
piston dome or the head gasket surface.
(1) CYLINDER HEAD
Cylinder Decarbonizing
Clean carbon deposits from the exhaust port and sub-
chamber areas.
CAUTION:
•
Do not damage the cylinder bore.
(1) EXHAUST PORT
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