Yamaha TT-R90(N) Owner's Service Manual page 166

CYLINDER HEAD
REMOVAL POINTS
Cylinder head
1. Align:
"I" mark
(with stationary pointer)
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
Align the "I" mark a on the rotor with the
stationary pointer b on the crankcase
cover. When the "I" mark is aligned with
the stationary pointer, the piston is at the
Top Dead Center (T.D.C.).
NOTE:
In order to be sure that the piston is at Top
Dead Center, the match mark c on the
camshaft sprocket must align with the sta-
tionary pointer d on the cylinder head as
shown in the illustration.
If there is no valve clearance, rotate the
crankshaft counterclockwise one turn.
2. Loosen:
Camshaft sprocket bolt 1
3. Remove:
Timing chain tensioner
Camshaft sprocket 2
NOTE:
Fasten a safety wire to the timing chain 3 to
prevent it from falling into the crankcase.
Remove the bolt 1 while holding the rotor
nut with a wrench.
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ENG