Yamaha MX775 - ENGINE SPEED IS UNEVEN; THE BATTERY IS NOT CHARGED

6-5
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TROUBLESHOOTING
OTHER TROUBLES
ENGINE SPEED IS UNEVEN
THE BATTERY IS NOT CHARGED
No. Checking steps Possible remedy
1 Check the fuel level. Add the fuel if it is insufficient.
2 Check if fuel has deteriorated. Replace the fuel.
3
Check the spark plugs for dirt and check the spark plug
gap.
Clean, adjust, or replace the spark
plugs.
4
Check if there is air suction from the throttle body assembly
joint, gasket, or throttle shaft.
• Tighten the throttle body assembly
nuts securely.
• Replace the throttle body assembly
joint or gasket with a new one.
5
Check if the main passages, such as the throttle body
assembly, are clogged.
Clean the parts.
6
Check the valve clearance.
(Refer to “ADJUSTING THE VALVE CLEARANCE” on
page 2-9)
Adjust the valve clearance.
7
Check the valve face and valve seat for wear.
(Refer to “VALVES” on page 3-27)
Resurface or replace the valve face and
valve seat.
8
Check if there is seizure, wear, or damage on the piston,
piston ring, or cylinder.
(Refer to “PISTONS, CAMSHAFT, CRANKCASE, AND
CRANKSHAFT” on page 3-38)
Rebore or replace the piston, piston ring
or cylinder.
No. Checking steps Possible remedy
1
Check the fuses.
(Refer to “CHECKING THE FUSES” on page 5-27)
Replace the fuse(s).
2 Check the battery.
• Clean the battery terminals.
• Recharge or replace the battery.
3
Check the stator coil.
(Refer to “CHECKING THE STATOR COIL ASSEMBLY” on
page 5-34)
Replace the stator coil assembly.
4
Check the rectifier/regulator.
(Refer to “CHECKING THE RECTIFIER/REGULATOR” on
page 5-35)
Replace the rectifier/regulator.
5
Check the entire charging system’s wiring.
(Refer to “CIRCUIT DIAGRAM” on page 5-1)
Properly connect or repair the charging
system’s wiring.
6 The charging system circuit is OK. —