No spark, trying to troubleshoot CDI or Magneto

[linnix13]

Have you really checked out the plug wire? Try unscrewing it from the cdi and using a automotive wire. Just cut it off clean and push hard as you screw the new plug wire in. Then put the little screw cap back on the plug so it hooks up to the auto style wire. Leave the white wire disconnected till you get it going again. Hope this helped.

View attachment 18290

wow thats the nicest looking set up i have seen!

 

[Stink Bike]

I had a similar problem and it was a faulty kill switch.You could try bypassing it.

 

[Junster]

Thanks linnix13. Ok relaxxx first make sure the ground (black) is getting good ground to the engine. Disconnect the white wire completely. Look over the white wire to make sure it isn't grounding to anything. Then take out the plug and get the bike with the rear wheel off the ground so you can turn the engine over easily. Take off the generator cover. Make sure the magnet wheel is spinning with the motor and make sure it is not contacting the generator frame when it's turning. It needs to be very close but never touching. Check the blue wire for output it's a pretty high voltage. Also check the cover wrapping on the generator coils. Look for a stray wire sticking out. Good Luck

 

[duivendyk]

Mysterious,looks like there might be a short on gen. coil, if you have diode and electrolytic cap make up negative going peak rectifier on WW,should read neg 15-20V to ground.

 

[relaxxx]

Thanks for the ideas, raising the rear wheel was a big help, I cranked the motor as fast as I could and my digital meter read around 80V AC on the black and blue wires. I could clearly see a spark this time so it's possible I just wasn't pushing the motor fast enough before. Both CDI's spark the same. I tried to start the motor and still no go. I had compression, I had spark and I had gas because unburned gas was dripping from the muffler. I though maybe I had bad gas, unscrewed the bowl from the carb and burned the gas inside. Then I cleaned the bowl, put it back and together and this time it fired right up. So I guess it was the carb all along.

 

[Junster]

Glad you got it running again..

 

[relaxxx]

It's running but to very good. Doesn't have the power it used to. and running quite rough. The fact that I don't see a spark when turning slow concerns me. There should be a spark every revolution I would think. This would explain rough running at slow speeds. Still wondering if I should replace magneto.

 

[stealthc9]

so your carb was to blame?? and what type of petcock is that? it looks nice ur set up is very clean.

 

[Junster]

relaxxx check your headbolts. Your motor is getting just to the point they may need a little tightening. Not to much though. Oh and stealthc9 if your talking about the pic I posted that's my bike. The blue handle petcock is from Sick Bike Parts. It's $9.95 and totally worth it. Really high quality ball valve.