Yamaha YZ 2018 Series, Owner'S Service Manual

Page: 33 / 402

STARTING AND BREAK-IN
1-21
ECA
NOTICE
If the starter motor will not turn when the
start switch is pushed, stop pushing it im-
mediately in order to avoid placing extra
load on the starter motor.
TIP
If the engine fail to start, fully open the throttle
grip and push the start switch few seconds to
clear the engine of the rich air-fuel mixture re-
tained in it.
4. When the engine starts running, warm this
up one or two minutes at a steady speed (of
3000 to 5000 r/min), and then return the
starter knob/idle screw to its original posi-
tion.
EWA
WARNING
Since exhaust gas contains harmful ingre-
dients, do not start or warm it up at an ill-
ventilated place or a closed narrow place.
5. To stop the engine, push the engine stop
switch “1”.
TIP
Continue pushing the engine stop switch till the
engine comes to a full stop.
EASB29B045
STARTING A WARM ENGINE
Follow the same procedure as for starting a
cold engine with the exception that the starter is
not required when the engine is warm.
TIP
If the engine fail to start, fully open the throttle
grip and push the start switch few seconds to
clear the engine of the rich air-fuel mixtare re-
tained in it.
EASB29B046
BREAK-IN PROCEDURES
A break-in is important so that rotating portion,
sliding surfaces, and mounted areas may fit
one another, and that the rider may become ac-
customed to the machine.
ECA
NOTICE
Before running, do maintenance on the air
filter element.
Refer to “CLEANING THE AIR FILTER ELE-
MENT” on page 3-12.
1. After warming up the engine, drive it for
about 20 minutes at a throttle opening of 1/2
or less.
2. Make a pit stop, and check mounted areas
for looseness, oil leaks, or other problems.
3. Then, drive it for about 40 minutes at a throt-
tle opening of 3/4 or less.
4. Make a pit stop again, and thoroughly check
mounted areas for looseness, oil leaks, or
other problems. Thorough checks and ad-
justments are required in particular for
stretch of cables, free play of the brake,
stretch of the drive chain, looseness of the
spoke, and so on.
ECA
NOTICE
After a break-in or after each race, always
check the points shown in “TORQUE-
CHECK POINTS” for tightening torques and
retighten them. (Refer to “TORQUE-CHECK
POINTS” on page 1-23.)
Also when the following parts are replaced,
a break-in is required.
• Cylinder and Crankshaft: A break-in is re-
quired for about an hour.
• Piston, Piston ring, Valve, Camshaft, and
Gear: A break-in is required for about 30
minutes at a throttle opening of 1/2 or less.
Observe the condition of the engine careful-
ly during a break-in.
For checkpoints for a break-in, see “MAIN-
TENANCE AFTER BREAK-IN”. If any prob-
lem is found, immediately stop the engine
and make a checkup.