Yamaha MM700F, Service Manual

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2-41
INSP
ADJ
CARBURETOR TUNING
Mid-range and high speed tuning
Adjustments are normally not required, but may some-
times be necessary, depending on temperatures,
altitude or both.
Mid-range speed and high speed tuning (from
1/4 to full-throttle) can be done by adjusting the main
jet.
CAUTION:
Never run the engine without the air intake si-
lencer installed. Severe engine damage may re-
sult.
1. Start the engine and operate the machine under
normal conditions to make sure that the engine
operates smoothly. Stop the engine.
2. Remove:
•
Spark plugs
3. Check:
•
Spark plug insulator
1
color
A medium to light tan color indicates normal
conditions.
Distinctly different color
→
Replace the main
jet.
4. The main jet should be adjusted on the basis of
the “Main jet selection chart”.
NOTE:
By checking the condition of the spark plugs, it is easy
to get some idea of the condition of the engine. This
may diagnose potential problems before engine dam-
age occurs.
High altitude tuning
Use the chart in CHAPTER 9 to select main jets
according to variations in elevation and temperature.
NOTE:
These jetting specifications are subject to change.
Consult the latest technical information from Yamaha
to be sure you have the most up-to-date jetting
specifications.
1
Clip
2
Jet needle
3
Pilot mixture screw
4
Main jet
SCH2805
SCH2810