TUN
9-2
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 discol-
oration of spark plug(s).
Normal
Over burned (too lean)
Oil fouled (too rich)
EFFECTS OF THE SETTING PARTS ON THE
THROTTLE VALVE OPENING
Throttle valve opening
Full-open
Full-closed
Discoloration Condition of spark plug
Normal
Insulator is dry and burnt
brown.
Over burned
(too lean)
Insulator is whitish.
Oil fouled
(too rich)
Insulator is sooty and wet.
Setting part
Throttle valve opening
Pilot jet
Pilot air screw
Diameter of
straight
portion
Clip position
Main jet
Jet ne
edle
Full-closed 1 / 4
1 / 2
3 / 4 Full-open
ENGINE