I am having trouble with a no spark scenario.It has CMG RT100 on sticker.I have tried removing the kill switch wire from cdi and still no spark. Have tested resistance of the trigger and power wires to the cdi and seem ok, 120 and 700 respectively. Unfortunately cdi is not an ordinary 5 pin but has does have 5 individual wires coming from it and unable to find a replacement to check..The wires on cdi are black/red, black, dark green, blue/white and black/white. It has a 6 wire ignition key. when I tested the kill switches I could not get open circuit in run position. that is when tested resistance from blk/w kill wire to engine ground with all kill switches in run I had continuity.This was done by removing the blk/w wire from the cdi and connecting my meter to the blk/w pin in the harness to ground, but all other wires of cdi still connected, So it seems I have a dud cdi or perhaps ignition switch or kill switch fault.????
Any help would be appreciated. If you are out there Lynn Edwards your response would be awesome.

 

Lynn Edwards doesn't seem to have posted for over two years, so I will try to help. Check if that black/white wire is still earthed when you switch ignition off. If it isn't, it looks like you have an earth to run CDI. Bad to test for, but check if you get any AC voltage output from the exciter coil and the trigger coil on the alternator when the engine is spun on the starter. With everything connected and ignition on, spin the engine over and check if you get high voltage pulses from CDI to ignition coil, if you do, but don't get a spark, it is the coil at fault. Most circa 100cc Chinese two strokes are the same, some recon it is a copy of a Minarelli engine, Polaris used it, along with a host of other makers, Apache still do, so wiring diagrams etc, for these machines may help with fault finding.

 

Thanks for your reply merryman. Sorry to hear lynn Edwards is not corresponding. Yes blk /w wire is grounded whether ignition off or on. I tested the ignition coil to ground and cranked over and got no ac voltage but lowest scale on my meter is 200. I think this may confirm my CDI is bad or could it be my ignition switch.....I still don't understand why I cannot get an open circuit whenl kill switches are off and ignition is on. Cheers

 

Yea me again with my no spark 100cc 2 stroke. The ignition switch does not have blk/w wire but has 6 other wires namely, black, green/red, yellow/brown, yellow, red and red/white. So does it not have a kill wire???? I am getting power to cdi 100v ignition power to ground but don't seem to be getting anything from the ignition coil wire to ground. Trigger pin to ground about 0.1 v. So is it the cdi or my ignition switch.???? Cannot find a replacement cdi to try. Any help appreciated.
Thanks carsonh

 

Switch is a standard one for these machines, if you trace the wires from the switch to the loom plug, I bet one of them plugs into a black/white. However, if you are getting 100v from the wire out of CDI to ignition coil, but no spark from coil, looks like that is where the fault lies. I have a diagram for these machines, but all the colours are different, so need to know wires by where it goes too and from, rather than it's colour.

 

Thanks merryman.. The 100v is to the cdi NOT from cdi. But no voltage when measuring from the ignition coil pin to ground. So I guess I have to look for another cdi.

 

…...another thing I noticed when I checked the trigger wire to ground and cranked over was that the battery was drained very quickly. This did not happen with any of the other voltage tests. Is that normal????? carsonh

 

Finally I have just tested the cdi earth wire connector in harness to engine ground and found open circuit, should it be 0 ohms. CAN THAT BE THE PROBLEM?????
carson

 

If you are sure it is the earth to CDI. Shows as a black on my diagram, other CDI wires are black/white to kill, orange for ignition coil, white/red and black/red to stator. New CDIs come with a warning that they will blow if they are run with the earth disconnected, so a faulty earth would probably blow the CDI. A CDI for any of these 2 stroke 90cc bikes (Polaris, Apache, etc,) would work, if you know how to wire it with different wiring colours.

Small batteries will soon go flat when you are cranking over a while without the engine starting.

 

I wired the cdi to frame ground but still no spark. Tried another cdi but the same result. So I am stumped. Even with the blk/w kill wire removed eliminating kill swithes didn't help.
Checked coil resistance and are ok. Is there anything else???? Cheers carsonh