Engine Break-In - Yamaha YZ85 Owner's Manual

Engine break-in

1. Before starting the engine, fill the
fuel tank with a break-in oil-fuel
mixture as follows.
Recommended 2-stroke engine oil:
See page 8-1.
Mixing ratio (gasoline to oil):
15:1
2. Start and warm up the engine.
Check the operation of the controls
and the engine stop button. (See
page 3-1.)
3. Operate the motorcycle in the low-
er gears at moderate throttle open-
ings for five to eight minutes. Stop
the engine and check the spark
plug condition (see page 6-8); it
will show a rich condition during
break-in.
4. Allow the engine to cool. Restart
the engine and operate the motor-
cycle as in the step above for five
minutes. Then, very briefly shift to
the higher gears and check the
full-throttle response. Stop the en-
gine and check the spark plug.
OPERATION AND IMPORTANT RIDING POINTS
EAU41502 5. After again allowing the engine to
cool, restart and run the motor-
cycle for five more minutes. Full
throttle and the higher gears may
be used, but sustained full-throttle
operation 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 cylinder.
Remove any high spots on the pis-
ton with #600-grit wet sandpaper.
Clean all components and careful-
ly reassemble the cylinder head
and cylinder.
WARNING
If you are not familiar with mainte-
nance work, have a Yamaha dealer
do it for you.
7. Drain the break-in oil-fuel mixture
from the fuel tank and refill with the
specified mix. (See page 3-3.)
8. Start the engine and check the op-
eration of the motorcycle through-
out its entire operating range. Stop
the engine and check the spark
After the engine break-in period, thor-
oughly check the motorcycle for loose
parts, oil leakage and any other prob-
lems. Be sure to inspect and make ad-
justments thoroughly, especially cable
and drive chain slack and loose
spokes. In addition, check all fittings
and fasteners for looseness, and tight-
en if necessary.
CAUTION:
G
EWA10320
5-3
plug condition. Restart the motor-
cycle and ride it for about 10 to 15
more minutes. The motorcycle will
now be ready to ride normally.
When any of the following parts
have been replaced, they must
be broken in.
Cylinder or crankshaft:
About one hour of break-in op-
eration is necessary.
Piston, rings or transmission
gears:
These parts require about 30
minutes of break-in operation at
half-throttle or less. Observe the
condition of the engine carefully
during operation.
5
ECA15560