Yamaha YZ85M 2021 Owner's Manual page 36

Operation and important riding points
the higher gears and check the
full-throttle response. Stop the en-
gine and check the spark plug.
5. After again allowing the engine to
cool, restart and run the motorcy-
cle for 5 more minutes. Full throttle
and the higher gears may be used,
but sustained full-throttle opera-
tion should be avoided. Stop the
engine and check the spark plug
again.
6. Allow the engine to cool, remove
the cylinder head and cylinder,
and inspect the piston and cylin-
der. Remove any high spots on
the piston with #600-grit wet
sandpaper. Clean all components
and carefully reassemble the cyl-
6
inder head and cylinder.
7. Drain the break-in oil-fuel mixture
from the fuel tank and refill with
the normal oil-fuel mixture. (See
page 4-4.)
8. Start the engine and check its
power delivery and throttle re-
sponse throughout all gear rang-
es. Stop the engine and check the
spark plug condition. It should be-
gin to lighten in color.
9. Restart the motorcycle and ride it
for about 10 to 15 more minutes.
Stop the engine and check the
spark plug condition. (See page
7-6.)
10. Lastly, thoroughly check the mo-
torcycle for loose parts, oil leak-
age and any other problems.
Check all fittings and fasteners
and tighten as necessary.
TIP
Be sure to inspect and make adjust-
ments thoroughly. In particular, check
control cable slack, drive chain slack
and for loose spokes.
Notes on engine overhauls
If the following parts have been re-
placed, they must be broken in as fol-
lows.
 Piston,
rings
gears: 30 minutes of break-in op-
eration at half-throttle or less.
 Cylinder or crankshaft: 60 minutes
of break-in operation is necessary.
TIP
Observe the condition of the engine
carefully during break-in operation.
NOTICE
If any engine trouble should occur
during the engine break-in period,
immediately have a Yamaha dealer
check the vehicle.
6-2
or transmission
ECA10271