PERIODIC MAINTENANCE AND MINOR REPAIR
6-18
6
EAU00630
Adjusting the carburetors The carburetors are important parts of
the engine and require very sophisti-
cated adjustment. Therefore, most car-
buretor adjustments should be left to a
Yamaha dealer, who has the neces-
sary professional knowledge and expe-
rience. The adjustment described in
the following section, however, may be
serviced by the owner as part of routine
maintenance.
EC000095
CAUTION:@ The carburetors have been set and
extensively tested at the Yamaha
factory. Changing these settings
without sufficient technical knowl-
edge may result in poor perfor-
mance of or damage to the engine. @
EAU00632
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.
1. Start the engine and warm it up for
several minutes at 1,000–
2,000 r/min while occasionally rev-
ving it to 4,000–5,000 r/min.NOTE:@ The engine is warm when it quickly re-
sponds to the throttle. @
2. Check the engine idling speed
and, if necessary, adjust it to spec-
ification by turning the throttle stop
screw. To increase the engine
idling speed, turn the screw in di-
rection
a. To decrease the engine
idling speed, turn the screw in di-
rection
b.NOTE:@ If the specified idling speed cannot be
obtained as described above, have a
Yamaha dealer make the adjustment. @ 1. Throttle stop screwEngine idling speed:
1,050–1,250 r/min
E_4tx.book Page 18 Wednesday, October 4, 2000 4:28 PM
PERIODIC MAINTENANCE AND MINOR REPAIR
6-45
6Engine overheating
EW000070
WARNING
@ l
Do not remove the radiator cap when the engine and radiator are hot. Scalding hot fluid and steam may be
blown out under pressure, which could cause serious injury. Be sure to wait until the engine has cooled.
l
After removing the radiator cap retaining bolt, place a thick rag, like a towel, over the radiator cap, and then
slowly rotate the cap counterclockwise to the detent to allow any residual pressure to escape. When the hiss-
ing sound has stopped, press down on the cap while turning it counterclockwise, and then remove the cap.
@NOTE:@ If coolant is not available, tap water can be temporarily used instead, provided that it is changed to the recommended coolant
as soon as possible. @
Wait until the
engine has cooled.
Check the coolant level in the
reservoir and radiator.
The coolant level
is OK.The coolant level is low.
Check the cooling system
for leakage.
Have a Yamaha dealer checkand repair the cooling system.Add coolant. (See NOTE.)
Start the engine. If the engine overheats again,
have a
Yamaha dealer check
and repair the cooling system.
There is
leakage.
There is
no leakage.
E_4tx.book Page 45 Wednesday, October 4, 2000 4:28 PM
