Post by lee82 on Oct 10, 2007 16:26:55 GMT -5
Summary-Trouble shooting GY6 no-spark problem.
When I started trouble shooting this problem I did not understand how the ignition system on the GY6 engine works. Lots of parts and lots of hours later I think I understand it better.
The stator coils perform two functions. Half of the coils provide positive and negative AC pulses to power the lights. The other half provide positive and negative AC pulses to the rectifier/regulator. These coils are inside the flywheel. The flywheel has the same number of magnets mounted in the rim as there are coils on the stator. There is a small magnet mounted on the outside of the flywheel that passes very close to a small coil mounted outside of the flywheel. Every time the magnet passes near the coil a timing pulse is sent to the CDI.
The rectifier/regulator shunts the negative half of the positive and negative AC pulses to ground, leaving only the positive pulses to power the CDI and regulate the battery charging
voltage.
The CDI provides power to the primary windings of the ignition coil. The voltage to the primary windings causes a much larger voltage buildup in the secondary winding of the ignition coil. This happens because there is a lot more secondary windings than there is primary windings.
When the trigger pulse is supplied to the CDI, the CDI removes voltage to the primary windings. Removing the voltage from the primary windings results in a rapid decline of the secondary voltage. This generates a large voltage spike. This voltage spike is added to by the voltage stored in the capacitor inside the CDI. The result of these two voltages is sent to the spark plug thru the high voltage lead. Hopefully, FIRE.
Determine if lack of spark is the problem.
1.Remove the spark plug.
2.Place your thumb over the spark plug hole.
3.Rotate the flywheel until you feel suction of the piston on the intake stroke stop.
4.Spray a shot of starter fluid into the cyclinder.
5.Replace the plug.
6.Try the starter.
7.Any firing of the plug indicates that you have spark.
Suggested troubleshooting sequence.
1.Replace the plug. Repeat the above procedure.
2.Still no spark. Find the CDI. My CDI has a four wire connector and a two wire connector. One of the wires going into the two wire connector is the timing pulse from the stator. The second wire is a black and white wire from the kill switch. When the kill switch is activated it applies a ground connection to the CDI and shorting the timing pulse to ground.
3.Clip this wire 8 to 10 inches from the CDI. Now you know the timing pulse is not being grounded by the kill switch, the ignition switch or a short in the wiring.
4.If that sucker don't run now the problem gets more serious. If it does run now replace the kill switch with the spare that you have ordered ahead of time. Right?
5.Reconnect the wire using a small butt connector.
6.If it is still not running, check the coil connections and the high tension lead where it attaches to the spark plug. I have read posts where the high tension leads have come apart internally. Still not running, borrow a buddys coil and high tension lead and substitute it for your coil and high tension lead.
7.The same goes for the CDI and rectifier/regulator.
8.Stators seem to be pretty troublefree for a number of years and should be looked at as a very last resort cause they are a real pain in the butt to replace. One way to check for output from the stator coils is by use of a test light. A standard 12 volt test light when connected between ground and an output lead from the stator will glow when the engine is turned by the starter and voltage is being generated. The output of the trigger pulse is to
weak to light a 12 volt test light but I think if a test light were created using a 3 volt flashlight bulb enough current would be generated that you would see the filement glow.
One last thought. I am going to replace my kill switch with a pushbutton switch. When I want to kill the engine, I will push it, when the engine is dead I will let up on the switch and the scoot is ready to start again. No longer have to worry about the kill switch being in the RUN position.
Hope this helps someone.
When I started trouble shooting this problem I did not understand how the ignition system on the GY6 engine works. Lots of parts and lots of hours later I think I understand it better.
The stator coils perform two functions. Half of the coils provide positive and negative AC pulses to power the lights. The other half provide positive and negative AC pulses to the rectifier/regulator. These coils are inside the flywheel. The flywheel has the same number of magnets mounted in the rim as there are coils on the stator. There is a small magnet mounted on the outside of the flywheel that passes very close to a small coil mounted outside of the flywheel. Every time the magnet passes near the coil a timing pulse is sent to the CDI.
The rectifier/regulator shunts the negative half of the positive and negative AC pulses to ground, leaving only the positive pulses to power the CDI and regulate the battery charging
voltage.
The CDI provides power to the primary windings of the ignition coil. The voltage to the primary windings causes a much larger voltage buildup in the secondary winding of the ignition coil. This happens because there is a lot more secondary windings than there is primary windings.
When the trigger pulse is supplied to the CDI, the CDI removes voltage to the primary windings. Removing the voltage from the primary windings results in a rapid decline of the secondary voltage. This generates a large voltage spike. This voltage spike is added to by the voltage stored in the capacitor inside the CDI. The result of these two voltages is sent to the spark plug thru the high voltage lead. Hopefully, FIRE.
Determine if lack of spark is the problem.
1.Remove the spark plug.
2.Place your thumb over the spark plug hole.
3.Rotate the flywheel until you feel suction of the piston on the intake stroke stop.
4.Spray a shot of starter fluid into the cyclinder.
5.Replace the plug.
6.Try the starter.
7.Any firing of the plug indicates that you have spark.
Suggested troubleshooting sequence.
1.Replace the plug. Repeat the above procedure.
2.Still no spark. Find the CDI. My CDI has a four wire connector and a two wire connector. One of the wires going into the two wire connector is the timing pulse from the stator. The second wire is a black and white wire from the kill switch. When the kill switch is activated it applies a ground connection to the CDI and shorting the timing pulse to ground.
3.Clip this wire 8 to 10 inches from the CDI. Now you know the timing pulse is not being grounded by the kill switch, the ignition switch or a short in the wiring.
4.If that sucker don't run now the problem gets more serious. If it does run now replace the kill switch with the spare that you have ordered ahead of time. Right?
5.Reconnect the wire using a small butt connector.
6.If it is still not running, check the coil connections and the high tension lead where it attaches to the spark plug. I have read posts where the high tension leads have come apart internally. Still not running, borrow a buddys coil and high tension lead and substitute it for your coil and high tension lead.
7.The same goes for the CDI and rectifier/regulator.
8.Stators seem to be pretty troublefree for a number of years and should be looked at as a very last resort cause they are a real pain in the butt to replace. One way to check for output from the stator coils is by use of a test light. A standard 12 volt test light when connected between ground and an output lead from the stator will glow when the engine is turned by the starter and voltage is being generated. The output of the trigger pulse is to
weak to light a 12 volt test light but I think if a test light were created using a 3 volt flashlight bulb enough current would be generated that you would see the filement glow.
One last thought. I am going to replace my kill switch with a pushbutton switch. When I want to kill the engine, I will push it, when the engine is dead I will let up on the switch and the scoot is ready to start again. No longer have to worry about the kill switch being in the RUN position.
Hope this helps someone.
