No Spark Help! By bikerbryce (Read 136 times)

[bikerbryce]

Ive got a Gy6 150 with no spark. The power wire from the stator measures ~40-60vAC when cranking, the trigger wire from stator measures .1vAC when cranking. The coil resistance is .1ohm and I tried the cdi on a working bike and the other bike started right up so it’s not the CDI. I think the issue is related to the wire from the CDI to the coil because when cranking I only get ~1vAC (both measured at coil and at the cdi) and it should be higher than 18vAC but I don’t understand how that could happen when the cdi works on a different bike. I also noticed that the green ground wire at the coil has about 120 ohms resistance to the negative terminal which is weird but I tried a jumper directly to the coil from the neg terminal with the same result. Any ideas what it could be? This is the guide I followed. Thanks in advance!

www.buggydepot.com/tech-center/gy6-150cc-ignition-troubleshooting-guide-no-spark/

[classacted]

one bike could be AC cdi system and the other could be DC cdi system. make sure you have more ground than you need. you can never have too much, but you can have not enough. any excess just won't be used.
spare parts are ridiculously cheap. buy extra cdi's, rectifiers, and coils. I buy a bunch of them and immediately try each one and label them like a scientist would.
those connections at the coil have to be crazy tight too.

[bikerbryce]

Aug 13, 2024 14:02:06 GMT -6 classacted said:

I guess I should’ve clarified, the new bike is also a Gy6 and I tried both CDIs on the working Gy6 and both worked perfectly. I suppose it’s possible the reason the bike was abandoned was cause it had the wrong cdi but I feel like that’s unlikely, I’ll look into it though. I would guess it’s the coil connection or ground at the cdi but I added a new ground connection so now there’s only about 5ohms resistance from the ground at the cdi, that’s why I’m confused the ground at the coil has high resistance. The output power wire to the coil from the cdi is measuring only ~1vAC even with the new ground connection at the cdi even though the input wires from the stator are at the proper voltage readings.

[bikerbryce]

I just did a little bit of research and it looks like mine are both AC cdi because they both have power supplied from the stator whereas DC cod has power taken directly from the battery and the stated just triggers the power to the coil.

[bikerbryce]

Just bumping this, still can’t figure out the issue. Could it be the pickup?

[bikerbryce]

I figured it out!! It was the ignition coil! Even though it was reading 1ohm resistance which is in the range, it wasn’t holding enough charge to send spark to the spark plug. When in doubt, check the coil according to this write up that has yet to fail me! www.buggydepot.com/tech-center/gy6-150cc-ignition-troubleshooting-guide-no-spark/