66cc no spark! please help!

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lucajo16

Member
Dec 12, 2013
100
2
16
cincinnati, ohio
Ok so I'm by now used to getting into the technical issues and repairing required by the 66cc engines but this one has me stumped. The other week I had to replace the magneto which I got the new one from a local shop. they did grind the gum off the mag. And it sparked for me for alittle while. But I think I over ran the engine the other day and it just failed to spark. At first I thought it was a spark plug which when I checked the plug it looked fouled so I went to a local auto shop and got an NGK B7HS cause its hot out....bought four. so I get back to where my bike is and put the plug in....no spark

So I looked at the CDI which it looked old. I took a multimeter to it and one connection read 47 ohms (( I had it set to 2000 ohms. )) the other one said zero so I thought it was the CDI....replaced that....no spark. I got the CDI From the same guy I got the mag from and the CDI connections looked tanned out like they have been used....he says there from sitting...idk.

At this point I'm ready to give up on this engine and get a new one. I don't want to take it to the mechanic cause he can be a pain in the ass to deal with. Please help obi wan your our (( me and my bike)) only hope!
:-||
 
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lucajo16

Member
Dec 12, 2013
100
2
16
cincinnati, ohio
Well when it comes to the mag do I pull it out of the engine or do I leave it in and check? And what ohms? I did it at the 2000 mark on my reader with the old cdi
 
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lucajo16

Member
Dec 12, 2013
100
2
16
cincinnati, ohio
Well I know as far as my testing is confirmed by the bike berry YouTube channel I'm doing it wrong. So when I get home I'm going to pull both out and retest them. I did get the 2000 ohms part right. I wasn't testing it right.
 
Kioshk

Kioshk

Active Member
Oct 21, 2012
1,152
10
38
Connecticut
You can test the armature-coil while it's in the engine.

If your coil has the 3rd white-wire, either isolate it or snip it off at the base; you won't need it.

The coil resistance should be around 320k-Ohms. If it's HUGE (basically infinite), your have a problem somewhere in the circuit.

Disconnect the black and blue wires from the CDI.

First check the resistance between the black and blue wires.

If it's not about 320k-ohms, check the resistance between the black-wire and anywhere on your engine-metal. This is ground and should be zero. If it's not, your ground is bad. If the black-wire is soldered to the coil, check the solder-joint. If it's connected to the armature under on of the screws, make sure the armature is grounded (check resistance between it and your engine-metal).

If the ground's good, check the blue-wire similarly. You should read about 320k-ohms between the blue-wire and the armature and the engine-metal.

Remember, the black-wire is "ground". It's just an extension of the engine/armature metal.
 
LandSpeedRecord

LandSpeedRecord

Dealer
Dec 11, 2014
628
14
18
Tucson
Not sure what your latest findings are. While you are at it with the multi meter set it to where it makes a tone for continuity then test all your wires tip to tip. I have found where the crimped on connector at the end of the mag wire simply wasn't touching the wire core. Zero dollar fix. If these parts work when they come out of the box they tend to work a long time but the factory connections are pretty weak on even the best kits. Hope this helps, let us know if you got going.
 
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