Test Run - Yamaha YZ125N1 Service Manual

A
B
C
SETTING
That is:
9Higher temperature expands the air with its
resultant reduced density.
9Higher humidity reduces the amount of oxygen
in the air by so much of the water vapor in the
same air.
9Lower atmospheric pressure (at a high altitude)
reduces the density of the air.
EC713001

Test run

After warming up the engine equipped with the
standard type carburetor(s) and spark plug(s),
run two or three laps of the circuit and check the
smooth operation of the engine and discoloration
of spark plug(s).
Discoloration
Normal
Over burned
(too lean)
Oil fouled
(too rich)
å Normal
∫ Over burned (too lean)
ç Oil fouled (too rich)
7-2
TUN
Condition of spark plug
Insulator is dry and
burnt brown.
Insulator is whitish.
Insulator is sooty and
wet.
7