Premature CDI Failure

[El Oso]

I have a People 150 that came to me as a no start. Replaced the solenoid, now states and stalls, starts and stalls. Removed and cleaned carb., reinstall, Starts and stalls, starts and stalls.   Now cranks but no start.  No spark, replaced CDI, starts and stalls, starts and stalls.  Now no spark again, what is eating the CDI?  Driving me nuts.  Thanks for any input.

[CROSSBOLT]

How do you know the CDI has failed?

[scooterfan]

Did you do a proper load test on the battery ? Your experience is a typical battery problem. The battery might not be fully charged, or not in good condition any longer.

You can do a Voltage test on the loose two pin plug at the CDI. Just un-plug the two pin plug, switch the ignition switch in "on" position, and have a look at what voltage reading you get at the pin on the loose two pin plug when you press the starter button.
If you get a voltage reading of about 9.5 Volts or less, you probably have a battery problem, not a CDI problem.

[El Oso]

Karl,
I suspect the CDI because the first time I lost spark and replaced it I regained spark but only for a short time.

Scooterfan,
I get 12.25 volts with the KO and 10.4 while cranking.

[scooterfan]

Scooterfan,
I get 12.25 volts with the KO and 10.4 while cranking.

Still perfect then !

Did you check the ignition coil, or a possible bad connection on the plug wire between the ignition coil and the spark plug ?

[scooterfan]

Scooterfan,
I get 12.25 volts with the KO and 10.4 while cranking.

Second thoughts - maybe I didn't understand your comment correctly.

Did you get the second voltage reading (10.4 volts) at the battery, or at the loose (unplugged) terminal which plugs into the CDI ?

There is no point in taking the second reading at the battery while the engine is cranking - the voltage test needs to be done at the terminal which plugs to the CDI when the engine is cranking.

[CROSSBOLT]

KO = key on?

[scooterfan]

KO = key on?

I think you’re right.
Main question though - where did that voltage reading (10.4 volt) came from - a voltage test at the battery terminals, or a voltage test at the loose plug which normally connects to the CDI ?

If the test was done at the battery, the voltage reading at the far end of the terminal could easily be lower than 9.5 Volts - which means the CDI would easily not work properly.

[El Oso]

KO= key on as far as the voltage readings the 12.25 was at the unplugged CDI with the key on and the 10.4 was at the same plug while cranking.  That being as it may I now have spark, I believe it was a bad connection on the coil.  However (I'm going to show my age here) back in the day when there were distributers and 1 coil on a car there was a ballast resistor mounted on the firewall to drop the voltage to the primary windings of the coil to 9 volts.  Well when that resistor went to the bad the engine would only run with the key in the start position and die as soon as you let the key return to the on position.  That is basicly what is happening to this scooter.

Thoughts?

Thanks,
Bear

[scooterfan]

..........................................That being as it may I now have spark, I believe it was a bad connection on the coil.

 However (I'm going to show my age here) back in the day when there were distributers and 1 coil on a car there was a ballast resistor mounted on the firewall to drop the voltage to the primary windings of the coil to 9 volts.  Well when that resistor went to the bad the engine would only run with the key in the start position and die as soon as you let the key return to the on position.  That is basicly what is happening to this scooter.

Thoughts?

Thanks,
Bear

Good to know that you got the scooter going.

The "ignition key part" of your reply is quite interesting.
On my scooter (Agility 125) the ignition key only has a power "Off" and power "On" position - there is no 'Start" position. The ignition switch on my scooter only has two wires connected to the switch - an incoming positive (+) feed from the battery, and only one outgoing positive feed to the CDI.
The only way to start my scooter (apart from the kick start) is to turn the ignition switch to the "On" position, (which means the CDI gets power (+) feed in advance directly from the battery) -  and then I need to press the starter button. When the engine needs to be switched off I just turn the ignition to the “off” position. Which means the power supply from the battery to the CDI gets switch off, and Bingo - the engine dies. Very simple - my scooter has a DC CDI and the engine will never run without power from the battery.

It sounds like in your case the ignition switch has a separate "Start" position, has at least three wires connected to the starter switch,  you can actually start the scooter without pressing a separate Starter button ?

I must admit - I actually believed all these scooter's starter wiring would be exactly the same ?

[tortoise]

now have spark

If intermittent . . troubleshoot trigger/pulsar/pickup coil.