Major electrical wierdness!

[mikesbike]

Hi guys, I'm new to this foum. I've got about 900 miles on my 48cc bike. It went about 200 miles like a champ. Then all of a sudden the weirdness that has become worse and worse. It is very difficult to start. It will only start if the kill switch is activated. It runs very poorly, (4cycleing?) If I can catch it just right I then have to push the button again and an IF I am really lucky it might go into a good 2cycle mode. If I don't kill the motor, it will run very nicely until I shut it off again. The thing won't even think about firing unless it gets grounded first. I've spent hours messing with wireing. I got a new magneto and it would not run at all with the new one under any circumstances. Can someone stear me to a fix? Would it be the CDI? I figure as good as it runs when it does start thats not it.

 

[gone_fishin]

let's start at the beginning:
CDI to Magneto
blue to blue/green (kill switch belongs here)
black to black
white capped or for light (for troubleshooting, disconnect any light)

plug-cable fully seated in cdi & boot firmly on plug

edit: correct plug gap posted below.

all good so far?

welcome to MBc 8)

 

[mikesbike]

I have the kill on the white. If the white is not grounded to the motor or frame. (Killed) the motor will not start. No way.

 

[gone_fishin]

using the replacement magneto, are you willing to try the proper wiring config for us?

 

[mikesbike]

I'll try anything. My starting ritual is pretty embarrasing! My bike looks good. I look stupid trying to get it to go.

 

[gone_fishin]

we all do!

make sure the connections are tight & well-insulated from the frame, and from each other, too.

 

[thatsdax]

Wiring problems..

Spark Plug gap should be 15-20 thousands. 30 thousands works ok for some autos..But not for this motor. Make you gap about half of that. There is not much to the electrical. Magneto, CDI, and plug wire and cap. Check all wire connections, Including the brass snap inside the plug cap. make sure you remove the spark plug crown and just have the threads showing. White wire is for Headlight and not for kill. It will work for kill but using it for kill can cause excessive quick heat ups and eventually ruin the Coil. Ohms between blue and black should be around 260 ohms disconnected. There is no way to check the CDI. Thanks..Enjoy the ride..

 

[gone_fishin]

ok, .015-.020 it is...thanks dax.

edited my blooper, i'm gonna go looking for other examples of the wrong info.

 

[mikesbike]

Thanks for the tips. I have an automotive coil wire to the plug. (NGK) gap'd at .030 It has to have a crown. Have dialectric grease at both ends of the plug wire. I'll try the different gap and try to get rid of the white wire? I don't care about the light.

 

[gone_fishin]

dax has corrected the proper gap to .015-.020, i see you missed that.

just cap off the white wire til later or never.