No Spark and Completely Baffled

[Mars4dude]

I was riding my 100cc motorized bicycle with less than 30 minutes on it and it quit running like it ran out of gas. That was 2 months ago and still cannot figure out the cause. Checked no spark and tested magneto and it was bad. Ordered 3 new magnetos and 3 CDIs. After they arrived installed all of them individually and still no spark. Magnetos test at 304, 315, and 342 Ohms and the CDIs tested 6.8, 7.2 and 7.4 Ohms. Here's the totally baffling part... When the magneto is tested with a dc 12 volt light bulb it is as bright as it can be as it flashes like a spark, but no spark past CDI. Check and cleaned all contacts in the bikes electrical system and disconnected the the kill switch, and 4 different CDIs, 3 different magnetos and still no spark??? I've never seen anything like it. I have a new magnet on order, yet really don't think that is the problem by the way it lights up a 12 volt bulb. I really hope someone can help me with this problem and when the motor runs again, I will share the solution. HELP

 

[wrench]

If your using the Chinese S/P that came with the kit it might be faulty , Get NGK S/P

 

[Mars4dude]

Good idea but no spark. Have tried 4 different new spark plugs. Still no spark... Thanks for the reply.

 

[Venice Motor Bikes]

Exactly how are you testing for spark?

Try disconnecting the kill button... Sometimes that goes bad & keeps the engine from running.
Also... sometimes having the CDI wires zip-tied to the frame too hard will cause problems.

 

[Mars4dude]

The ways I've tested for spark are by grounding the spark plug on the motor and turning the motor over and watching the spark plug for spark (usually in the dark), I have 12 volt LED light bulb which requires 12 volts to light up and I have tested Magneto from the engine which lights up like I'm getting great spark and I have used on the CDI from the spark plug wire to a ground on the engine, NOTHING, and the resistance (Ohms) as stated above. There are zip ties on frame holding CDI wires. I've nerve heard of that. Good one to check out, if that does the trick I will let you know within an hour. The motor isn't grounded to the frame very well as the bike is painted. Could un-grounded motor cause no spark past the CDI? TY for the suggestions. To me this problem defies laws of physics.

 

[Mars4dude]

Almost forgot, the kill switch is disconnected but does test okay.

 

[Greg58]

I sand the back of the coil to get good contact to the engine case, it is also better to solder the wires from coil to cdi and srink wrap them. Ignition problems will drive you nuts.

 

[Greg58]

Play with the plug gap also, 26-28 has worked best for me.