Yamaha TTR 125 2020, Owner'S Manual

Page: 48 / 86

Perio d ic maintenance an d a d justment
7-13
7
EAU39931
A d justin g the car b uretor
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
ECA10551
The car b uretor has b een set an d ex-
tensively teste d at the Yamaha fac-
tory. Chan g in g these settin g s
without sufficient technical knowl-
e
dg e may result in poor perfor-
mance of or d ama g e to the en g ine.
EAU21363
A d justin g the en g ine i d lin g
spee d
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.
1. Attach the tachometer to the
spark plug lead.
2. Start the engine and warm it up for
several minutes at 1000–2000
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
direction (a). To decrease the en-
gine idling speed, turn the screw in
direction (b).
TIP
If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment.
1. Throttle stop screw
En g ine i d lin g spee d :
1300–1500 r/min
U2PT17E0.book Page 13 Monday, March 30, 2020 2:13 PM