had some issues with with one of my sons bikes dying in the woods,
bmx atv with loncin 110 engine. finally got it running again, but now it wont shut off with either the key or the kill switch???? any ideas?

thanks

 

Does your CDI look like this?





This is the most common type. If you have a four pin CDI instead of the 5 pin above then we'll have to start over and go down a different path.

On the 5 pin CDI the engine is shut off by grounding the "Kill Switch" pin via one or more kill switches all tied onto that pin. When any one of the switches shorts the kill pin to ground the spark stops and therefore so does the engine. Often this is a black wire with a white stripe.

Since none of your kill switches work then you probably have a broken wire to the CDI. Try starting the quad and shorting the kill pin to ground with a jumper wire right at the CDI. If that works to stop the engine look for the broken wire on the way to the various kill switches (one side of the ignition switch, left handlebar kill switch, tether pull kill switch, and remote start/stop control module). CAUTION: The kill switch pin has high voltage on it (100-300 volts) when the quad is cranking or running, so don't get your fingers in the circuit. Use insulated pliers to hold whatever you use to make that ground connection to the kill pin.

Do you have the remote control module on this quad? Is it unplugged? If so the quad operation changes a little - the ignition switch can no longer shut off the quad, only the tether or left handle bar kill switch can do that. If you just happened to have a bad kill switch and the remote module is unplugged then you wouldn't be able to shut off the quad with the ignition switch.

 

thanks lynn!

I will check it out and see what I find.
It does have a remote control module, and yes it is out of the machine.
I could not get it to run with it in, all was good with two of the three plugs hooked up, as soon as i hooked up the third it would die.


I am going to look into it this weekend. Thanks for your expertise!!

 

ok, it shuts off when i ground out the kill pin. traced the ground kill switch wires with a meter at the kill switch, tether, remote connection and ignition. all seem ok.

neither handle bar kill switch or ignition will kill it

still when i plug in the third remote plug (grey and pink wires going to the cdi kill switch), it shuts off and will not start with it pluged in.

should i just wire a new kill switch to the cdi? i want to sell the machine, but want it to be safe for someone elses child.

 

So you traced the kill wire all the way up to the left handlebar kill switch. I'm assuming then that the kill switch isn't working - i.e. when you measure the at kill switch itself it doesn't short the kill switch wire to engine ground when the kill switch is pushed?

You could wire in a new kill switch if you like. Just wire it in parallel with the rest such that the kill wire is grounded when you want the engine to stop, and it is open when the engine is supposed to run.

From a safety standpoint I think a handlebar kill switch is a necessity. What if the throttle sticks wide open? The natural reaction is to clamp on the brakes and not let go of the handlebars. Without a handlebar kill switch how would you stop the engine?

The ignition switch can be made to kill the engine again by adding a jumper to the remote module connector. It may take some sleuthing to figure out which two wires these are but it shouldn't be too hard. What are the wire colors on the ignition switch? What are the wire colors on the remote module connector(s), and if you know where they go then report back (like the short antenna wire ot the wires to the audible alarm, etc.). What is the wire color of the kill switch connection at the CDI?