Yamaha TW125 1999, Service Manual

Page: 102 / 283

4-8
CYLINDER HEAD
ENG
NOTE:
NOTE:
NOTE:
4. Remove:
cylinder head
Loosen the nuts in the proper sequence.
Loosen each nut 1 / 2 of a turn at a time.
After all of the nuts are fully loosened, remove
them.
EAS00227
CHECKING THE CYLINDER HEAD
1. Eliminate:
combustion chamber carbon deposits
(with a rounded scraper)
Do not use a sharp instrument to avoid damag-
ing or scratching:
spark plug threads
valve seats
2. Check:
cylinder head
Damage / scratches
Replace.
3. Measure:
cylinder head warpage
Out of specification
Resurface the cylin-
der head.
Cylinder head warpage
Less than 0.05 mm
a. Place a straightedge 1 and a thickness
gauge
2
across the cylinder head.
b. Measure the warpage.
c. If the limited is exceeded, resurface the cylin-
der head as follows.
d. Place a 400 600 grit wet abrasive paper
on the surface plate and resurface the cylin-
der head using a figure-eight sanding pat-
tern.
To ensure an even surface, rotate the cylinder
head several times.