34
INSP
ADJ
Troubleshooting
Main jet selection chart
Spark plug color
Diagnosis
Remedy
Light tan or gray
Carburetors are tuned prop-
erly.
Dry black or fluffy
deposits
Mixture is too rich.
Replace the main jet with the next smaller size.
White or light gray
Mixture is too lean.
Replace the main jet with the next larger size.
White or gray insulator
with small black or
grayish brown spots
and electrodes having a
bluish-burnt appear-
ance
Mixture is too lean. The piston
is damaged or seized.
Replace the piston and spark plug.
Tune the carburetors again. Begin with low-speed
tuning.
Melted electrodes and
possibly a blistered
insulator
Metallic deposits on
insulator
Mixture is too lean. The spark
plug melted.
Check the piston for holes or seizure.
Check the cooling system, gasoline octane rating
and ignition timing. After replacing the spark plug
with a colder type, tune the carburetors again.
Begin with low-speed tuning.
Trouble
Diagnosis
Adjustment
Hard starting
Insufficient fuel
Add gasoline.
Excessive use of the starter or
choke
Return the starter lever to its seated position so
that the starter valve is fully closed.
Fuel passage is clogged or
frozen
• Check and, if necessary, clean the fuel tank air
vent, the fuel filter and all of the fuel passages.
• Check and, if necessary, clean the carburetor
air vents, fuel passages and the float valve.
• Clean the float chamber of any ice or water.
Overflow
Adjust the fuel level.
Poor idling:
• Poor performance at
low speeds
• Poor acceleration
• Slow response to
throttle
• Engine tends to stall
Improper idling speed adjust-
ment
Adjust the engine idle speed.
Refer to “Low-speed tuning”.
Clogged bypass hole
Clean the bypass hole.
Clogged or loose pilot jet
• Remove the pilot jet, clean it with compressed
air and then install it.
• Make sure that the pilot jet is fully tightened.
Air leaking into the carburetor
joint
Retighten the clamp screws on the carburetor
joints.
Defective starter valve seat
Clean or replace the starter valve seat.
Overflow
Adjust the fuel level.
Poor performance at
mid-range speeds:
• Momentary slow
response to the throt-
tle
• Poor acceleration
Clogged or loose pilot jet
• Remove the pilot jet, clean it with compressed
air, and then install it.
• Make sure that the pilot jet is fully tightened.
Lean mixture
Overhaul the carburetors.
Summary of Contents for VK10L
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Page 84: ...32 INSP ADJ CARBURETOR TUNING Guide for carburetion ...
Page 111: ...INSP ADJ ...
Page 289: ...SPEC ...
Page 311: ...SPEC ...
Page 333: ...SPEC ...
Page 340: ...147 SPEC CABLE ROUTING A A A A 1 2 3 4 5 6 7 ...
Page 346: ...153 SPEC CABLE ROUTING 1 2 3 4 5 6 7 8 9 0 A B C D ...
Page 348: ...155 SPEC CABLE ROUTING B A A B A A E 8 9 9 0 0 A B C D 1 2 3 4 5 6 7 ...
Page 350: ...157 SPEC CABLE ROUTING A A 8 9 A 0 B 1 2 3 4 5 5 6 7 A A ...
Page 352: ...159 SPEC CABLE ROUTING A A 7 8 1 2 3 4 6 5 ...
Page 354: ...161 SPEC CABLE ROUTING 0 1 2 9 6 7 8 3 4 3 4 5 ...
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