Engine Speed Is Uneven; The Battery Is Not Charged - Yamaha MX775 Service Manual

OTHER TROUBLES

ENGINE SPEED IS UNEVEN

No.
1 Check the fuel level.
2 Check if fuel has deteriorated.
Check the spark plugs for dirt and check the spark plug
3
gap.
Check if there is air suction from the throttle body assembly
4
joint, gasket, or throttle shaft.
Check if the main passages, such as the throttle body
5
assembly, are clogged.
Check the valve clearance.
6 (Refer to "ADJUSTING THE VALVE CLEARANCE" on
page 2-9)
Check the valve face and valve seat for wear.
7
(Refer to "VALVES" on page 3-27)
Check if there is seizure, wear, or damage on the piston,
piston ring, or cylinder.
8
(Refer to "PISTONS, CAMSHAFT, CRANKCASE, AND
CRANKSHAFT" on page 3-38)

THE BATTERY IS NOT CHARGED

No.
Check the fuses.
1
(Refer to "CHECKING THE FUSES" on page 5-27)
2 Check the battery.
Check the stator coil.
3 (Refer to "CHECKING THE STATOR COIL ASSEMBLY" on
page 5-34)
Check the rectifier/regulator.
4 (Refer to "CHECKING THE RECTIFIER/REGULATOR" on
page 5-35)
Check the entire charging system's wiring.
5
(Refer to "CIRCUIT DIAGRAM" on page 5-1)
6 The charging system circuit is OK.
Checking steps
Checking steps
6-5
Possible remedy
Add the fuel if it is insufficient.
Replace the fuel.
Clean, adjust, or replace the spark
plugs.
• Tighten the throttle body assembly
nuts securely.
• Replace the throttle body assembly
joint or gasket with a new one.
Clean the parts.
Adjust the valve clearance.
Resurface or replace the valve face and
valve seat.
Rebore or replace the piston, piston ring
or cylinder.
Possible remedy
Replace the fuse(s).
• Clean the battery terminals.
• Recharge or replace the battery.
Replace the stator coil assembly.
Replace the rectifier/regulator.
Properly connect or repair the charging
system's wiring.
—
1
2
3
4
5
6
7
8
9
10