Another no-a-gs thing becuase you guys are smart

[makenzie71]

Another Lifan electrical issue. I got intermittent spark on my Hi Bird QH 250 ST. Sometimes I got excellent spark. Other times I got none at all. I've completely eliminated the wiring harness as a culprit. Built a new one and had the same problem. So it's got to be a component issue...either stator, pickup, cdi, or coil.

Here are my checks:

Stator, 3 yellow wires. .9ohms between each, no fluctuation. No continuity between the leads and ground.

Black w/red stripe, goes to CDI as AC Ignition Power. 1vac going to this plug when cranking.

Blue w/white stripe, goes to CDI as Ignition Trigger Pulse. I have something like .3vac when cranking.

Green w/white stripe, goes to the frame.

CDI. Kill circuit has been completely removed. I have voltage at trigger pulse and ac power. No output going to coil. Tried another CDI...either it has the exact same problem or the problem lay elsewhere.

I don't know what specs the coil is suppose to see...but I know if I put it on my 110cc quad it works properly.

Does any of this throw up an obvious red flag? Is that enough voltage going to the CDI on cranking?

[makenzie71]

Also:

Black w/red stripe, resistance to ground is 258ohms

Blue w/white stripe, no continuity to ground. I think this is my culprit. It should read similar to the other, if I understand it correctly.

[Matchless]

Also:

Black w/red stripe, resistance to ground is 258ohms

Blue w/white stripe, no continuity to ground. I think this is my culprit. It should read similar to the other, if I understand it correctly.

The source coil in your stator has one side grounded and the other going to the CDI on the black/red wire. It puts out about 90V AC, but cannot be measured with a slow multimeter. The resistance of the coil is usually about 250 - 350 ohm. You seem to be OK.

The pickup coil is also grounded on one side and the other goes to the blue/white wire and also has a resistance of about 250 ohms.

OK you have proved your fault to the pickup coil. Pull the cover and test right on the coil maybe you are lucky and the blue/white wire is the culprit!
You did not really need help!!

[makenzie71]

What a twist in the plot!

Today I check everything and I have continuity and ohms and everything where it's all supposed to be all the way up to the CDI (that part unchanged).

However, I shorted the hell out of my myself while moving the CDI and cranking and then I have spark. It went away after some moving around of bits and pieces.

I played a bit more with the cdi. I have the kill switch wire just dangling, but I'm pretty sure that's what go me...so I ground it while cranking. No spark. I release the kill switch wire, while still cranking, and get a spark. One spark as the ground is broken. I do it again, same result. Again, same result. After a couple times doing this the coil just starts blasting away.

What does that mean?

[Matchless]

What a twist in the plot!

Today I check everything and I have continuity and ohms and everything where it's all supposed to be all the way up to the CDI (that part unchanged).

However, I shorted the hell out of my myself while moving the CDI and cranking and then I have spark. It went away after some moving around of bits and pieces.

I played a bit more with the cdi. I have the kill switch wire just dangling, but I'm pretty sure that's what go me...so I ground it while cranking. No spark. I release the kill switch wire, while still cranking, and get a spark. One spark as the ground is broken. I do it again, same result. Again, same result. After a couple times doing this the coil just starts blasting away.

What does that mean?

Check out the black/white wire and the killswitch. It should send a ground to the CDI to stop the engine by inhibiting the spark and start it sparking when the killswitch is on run. It probably picks up the ground from the handlebars or should have a separate ground wire. Check for grounding, chafing of the black/white wire as well.

[makenzie71]

There is no kill switch circuit. The wire from the CDI which would normally be the source for the kill switch doesn't go anywhere.

[Matchless]

I played a bit more with the cdi. I have the kill switch wire just dangling, but I'm pretty sure that's what go me...so I ground it while cranking. No spark. I release the kill switch wire, while still cranking, and get a spark.

That kill switch wire also goes to the ignition switch. What happens if you completely remove the black/white wire on the CDI?

[makenzie71]

That;s been bypassed. The only thing the key switch does is supply power to the start button. When I get the rest of this sorted I'll probably put in a contact button kill switch, but right now the kill circuit is completely open.

[Matchless]

OK, assuming the wiring is all OK and all connecters are clean and good the next suspect will be the coil, HT lead, plug cap and plug. If these are good the CDI is your next stop. You never mentioned what type of bike it is, but going by the wire colours it may have a CDI that looks like this:

This will be your next suspect.

[makenzie71]

I wrote what bike it is in the very first line of written text in this thread lol. That particular CDI is for the Yamaha V-Twin knock-offs, but mine is similar. I have no voltage leaving the CDI for the coil.

I got my new CDI today, but it wasn't EXACTLY the same. It has a the same plugs, but also an additional red wire just dangling from the sealant on the bottom. I tried running this and got no spark...so I ran the red wire to the positive battery terminal and got nice pretty spark. I'm curious why the extra red wire...hope it's actually supposed to be charged. I guess I'll see.

[Matchless]

Sorry, I did see that now that I checked again, must be age or something.... There are CDI's that are AC powered and use a source coil and there are some that are DC powered from 12 V. They have a small transformer to help step up the voltage and may be bigger in size.
I am not familiar with a separate wire as yours now has, but either one should work.
It seems that you now have it sorted anyway.

[makenzie71]

I hope I do...I rode about a mile without too much drama. Still needs a lot of work to run correctly, but it is running. Front shocks really, really suck...think walks all over the place.