2004 YAMAHA TT600RE seats

ENGENGINE DISASSEMBLY
5-19
VALVES
NOTE:
The valves may be inspected with the engine
installed by removing the following parts.
•Seat
•Fuel tank
•Exhaust pipe
•Carburetor
•Cylinder head cover
•Cylinder head
1. Check:
•Valve seal
Leakage from valve seats’ Inspect the
valve surface, the seat and seat width.
See section “VALVE SEAT INSPECTION
AND REPAIR”.
NOTE:
Check the valve seal before assembling the inter-
nal parts of the cylinder head (valves, valve
springs, spring retainer etc).
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Inspection steps:
•Pour clean solvent (1) into the intake and
exhaust ports.
•Check the valve seal. There must be no blow-
bys from the valve seats (2).
ProCarManuals.com

ENGINSPECTION AND REPAIR
5-21
INSPECTION AND REPAIR
CYLINDER HEAD
1. Eliminate:
•Carbon deposits
(from combustion chamber)
Use a rounded scraper (1).
NOTE:
Do not use a pointed tool to avoid damaging or
scratching:
•spark plug thread
•valve seats
•combustion chamber
2. Inspect:
•Cylinder head
Scratches/Damage ➔Replace.
3. Measure:
•Deformation
Out of specification ➔Rework the surface.
Cylinder head deformation: Less than 0.03 mm
4. Surface:
•Cylinder head
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Levelling:
Level the cylinder head with wet 400 ~ 600 emery
paper in a figure-8 direction.
NOTE:
To avoid removing too much material on one side
only, turn the cylinder head a number of times.
ProCarManuals.com

INSPECTION AND REPAIR
5-32
ENG
PISTON RINGS
1. Measure:
•Side clearance of rings
Use a thickness gauge.
Out of specification ➔Replace piston.
NOTE:
Before measuring side clearance, remove carbon
deposits from the piston ring seats and from the
rings themselves.
Piston ring side clearance
(installed):
Upper ring 0.04 ~ 0.08 mm
Lower ring 0.03 ~ 0.07 mm
: 0.13 mm
Oil scraper 0.02 ~ 0.06 mm
Piston ring end gap
(fitted into cylinder):
Upper ring 0.30 ~ 0.45 mm
: 0.7 mm
Lower ring 0.30 ~ 0.45 mm
: 0.8 mm
Oil scraper (tracks) 0.20 ~ 0.70 mm
2. Install:
•Ring (into the cylinder)
NOTE:
Fit each ring into the cylinder and push it to about
20 mm from the top edge of the cylinder. Push the
ring into the cylinder with the piston so that it is
perfectly perpendicular to the cylinder axis.
(a) 20 mm
3. Measure:
•Ring end gap Out of specification ➔Replace.
NOTE:
It is impossible to measure the oil scraper end
gap. If the oil scraper port appears too large,
replace all three rings.
ProCarManuals.com