Magneto fine, CDI apparently fine, sparkplug fine, NO SPARK! need help!

[skinnerman]

Hi! I'm new here. . .

So I just bought my bike and it's been working fine, well, kinda for a week.
Anyways my engine just stopped one day, and I noticed I wasn't getting a spark. So here goes.

My magneto seems to be working fine, I get around 30+ AC volts between the blue and black wires,
and the engine is properly grounded. But when I run all the ohm checks I only get 500 ohms between the black and blue wires
(red lead from meter on black and black lead from meter on blue) when I should 130k - 150k. The magneto is also soaked in oil, yet it still produces the 30+ vAC.

The kill switch is also fine. All the connecting wires are fine and there is no bare contacts or shorts.

The CDI shocks me quite a bit when I go fast, but when I put a spark plug on it, nothing happens, and even when I hold the spark plug I don't get shocked. If I take the spark plug out and touch the contact inside the spark plug cap I get shocked.

But there's no spark! Why!? (btw, I've done this test with 2 different spark plugs).

So it's not the spark plug because I tried several, it's not the magneto because it outputting 30+ vAC, and all the wiring is properly insulated, kill switch works, CDI shocks me, but no spark! Is this a grounding issue? Please help!

 

[2door]

Welcome to the forum. Hope we can help you.

Key words here are, "magneto soaked in oil". That is the problem. You probably have a bad crankshaft seal behind the magneto rotor (magnet).

30 volt output is low. Normal is about 80 volts. Replace the magneto coil and you should be good to go. To check the plug you need to ground it to the engine case while spinning the crankshaft. Holding it in your hand won't tell you much.
Good luck and let us know how things work out.

Tom

 

[skinnerman]

Finally someone who knows what they are talking about! I asked on another forum and the guy told me if the magneto is producing 30 volts AC then it's fine. Okaydokey I will get another one. How am I supposed to seal the case, like cover the crack with JBweld or something?

Is there any hope for my magneto, maybe some vigorous cleaning? It's semi-working

I've always wondered about the spark plug, because I know that the engine frame is the ground, but everybody tells you to take the plug out and hold it! But when you hold it you do get a small spark, so I guess your body must be acting as a ground when you are touching the metal on your bike?

Thanks Tom!