Adjusting The Carburetor; Adjusting The Engine Idling Speed - Yamaha TTR 125 2020 Owner's Manual

Periodic maintenance and adjustment

Adjusting the carburetor

The carburetor is an important part of
the engine and requires very sophisti-
cated adjustment. Therefore, most
carburetor adjustments should be left
to a Yamaha dealer, who has the nec-
essary professional knowledge and ex-
perience. The adjustment described in
the following section, however, may be
serviced by the owner as part of rou-
tine maintenance.
NOTICE
7
The carburetor has been set and ex-
tensively tested at the Yamaha fac-
tory. Changing
without sufficient technical knowl-
edge may result in poor perfor-
mance of or damage to the engine.
EAU39931
Adjusting the engine idling
speed
The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
TIP
A diagnostic tachometer is needed to
make this adjustment.
ECA10551
1. Attach the tachometer to the
spark plug lead.
2. Start the engine and warm it up for
several minutes at 1000–2000
these settings
r/min while occasionally revving it
to 4000–5000 r/min.
TIP
The engine is warm when it quickly re-
sponds to the throttle.
3. Check the engine idling speed
and, if necessary, adjust it to
specification by turning the throt-
tle stop screw. To increase the en-
gine idling speed, turn the screw in
EAU21363
1. Throttle stop screw
TIP
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
7-13
direction (a). To decrease the en-
gine idling speed, turn the screw in
direction (b).
Engine idling speed:
1300–1500 r/min