Removing The Cylinder And Piston; Checking The Cylinder Head - Yamaha YJ50RN Service Manual

CYLINDER HEAD, CYLINDER AND PISTON
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EAS00253

REMOVING THE CYLINDER AND PISTON

1. Remove:
2
• piston pin clip 1
• piston pin 2
• piston 3
CAUTION:
@
Do not use a hammer to drive the piston
pin out.
NOTE:
@
Before removing the piston pin clip, cover the
crankcase opening with a clean rag to prevent
the piston pin clip from falling into the crank-
case.
2. Remove:
• piston ring
NOTE:
@
When removing a piston ring, open the end
gap with your fingers and lift the other side of
the ring over the piston crown.
EAS00227

CHECKING THE CYLINDER HEAD

1. Eliminate:
• combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
@
Do not use a sharp instrument to avoid damag-
ing or scratching:
• spark plug bore threads
2. Check:
• cylinder head
Damage/scratches → Replace.
3. Measure:
• cylinder head warpage
Out of specification → Resurface the cylin-
der head.
Maximum cylinder head warpage
0.05 mm (0.002 in)
5 - 6
ENG
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