Joyner JNSZ250DN Owner's Manual page 25

a. Remove the spark plug and inspect it
(Use a spark plug wrench) The electrodes should be kept clean and free of
carbon. The presence of carbon or excess oil will greatly reduce proper engine
performance. If possible, check the spark plug gap (area between electrodes)
using a wire feeler gauge. This specification is 0.025"~0.030". (See Fig. 11)
b. Before installing spark plug coat threads lightly with graphite grease if
possible, to ensure easy removal next time the spark plug needs inspection.
c. It is advisable to replace the spark plug at least once a year to insure easy
starting and good engine performance.
E. Carburetor Adjustment
Never make unnecessary adjustments. The factory recommended settings
are correct for most applications. It's not necessary to disassemble the screw
unless the carburetor needs to be replaced. Prepare a 50r/w tachometer before
adjustment.
a. Warm up the engine (5~10min)
b. Tighten the airscrew gentle. Back out 2-3/8 turns counter clockwise.
c. Connect the tachometer; adjust the throttle to limit the idle speed. The
standard value is (1500RPM).
d. Turn the airscrew slowly and observe the RPM of the engine, stop adjusting
as the RPM reaches the top speed.
e. Adjust the screw and adjust the idle speed to an ideal value.
f. Repeat step d and e until the rotate speed of engine stables.
F. Cleaning Instructions
Keep your kart clean. With a clean rag, wipe off and dirt and oil from around
controls. Wipe off any spilled fuel and oil. Keep the engine clean off foreign object
and be sure to check that air intake fan is free off debris for proper cooling.
G. Kart Lubrication
Lubricate vehicle every 90 days of use, Apply several drops of oil in specific
points.
H. Chain Lubrication
To increase chain life, it should be lubricated with a spray on type chain
lubricant.
I. Chain Adjustment
Check the chain adjustment after first two hours of use. Readjust if it has more
than 1/2" flex. (See figure 13)
a. Loosen NUT #1, and NUT #2.
b. Rotate BOLT #1, the BEARING BLOCK will move forwards or backwards, so
Figure 12
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