CDI issue

[ca1987]

When I crank, my CDI boxes go from sending 12 volts to the coil down to just about nothing (0.5 volts) over a period of about 30 seconds then stay there. So I'll crank and watch it go from 12 to maybe 9 volts, then stop for 10 seconds or so, then crank and watch it go from 9 down and down to 4 volts, stop, try again and down and down it goes. Meanwhile the stator is putting out a steady voltage into the box.

They are AC (6-wire) CDI boxes and I've tried 4 of them now. I've been through 3 coils. I'm using a single stage hotter plug to help it fire.

At this point I think something may be wrong with the stator but it puts out a constant 33 volts AC when cranking so it doesn't look like anything's wrong with it.

I can't get a good enough spark to start the engine unless I am getting 12 volts out of that CDI box to the coil, and that only happens for the first few seconds of the life of the CDI and then sometimes if I have the bike sit for a few days and come back, I've noticed I can get a CDI to start back at 12 volts and do the same decline in output voltage.

The only way I've been able to start the bike is by cranking it with 400 amps real fast a few times until it starts. Once it starts it's good - there is no misfiring or anything and I can ride it as long as I want but as soon as I turn it off I can't get a good enough spark to start it.

I had one CDI box last for about an hour run time and I started and stopped it 5 or 6 times that night before garaging it (thinking it was fixed) and going to start my bike the next day and having the same issue.

 

[regal7point5]

What bike do you have?

 

[Rich Ard]

I'm going to venture a guess that your CDI is activated by a pickup coil at the rotor - have you done the diagnostics for the pickup as described in your manual?

 

[mydlyfkryzis]

What bike do you have?

I think I saw it...It had 2 wheels, a headlight and handlebars...does that help?

 

[ca1987]

I have a Lifan 200cc engine. No manuals come with these engines.

I can't get it to start even with the increased amperage now. When I turn up the amperage I get 43 volts AC from the stator to the CDI and from the CDI it is reading as drawing current now -2.2 volts whether I crank with 2 amps or 200.

The signal to fire the CDI seems good too- just like my main hot wire.

The resistance value between the two wires coming from the stator coil is 468 ohms. I don't have a figure on what that should be yet.

Do you have any ideas on tests I could run? I am searching online and will post more if I find any leads.

 

[Rich Ard]

That sounds pretty good to me, in re the pickup coil.

MAy be that your starter motor is finished, then, if you've replaced the CDI several times, you're getting voltage drop at the CDI when you crank, but nothing's movin'. Is the starter motor getting hot when you push the button?

 

[ca1987]

Starter motor is fine. It's not that nothing is moving, it's that voltage goes into the CDI box but doesn't come out and get to the ignition coil so I get no or weak spark.

My setup is battery sends power to the starter motor, which turns the crank, causes the pickup coil to generate AC, sends it to the CDI, sends it to the ignition coil to make the spark. So it will spin and spin and spin and voltage will be going into the CDI but not coming out of it.

I am taking out the stator for inspection and possible replacement today.

 

[mydlyfkryzis]

Is this the unit you need?

http://www.ebay.com/itm/NEW-DC-CDI-FOR-LIFAN-LF125-GY125-GY-125-150-200-CG-125-/221155330658

$13.00 Shipped?

 

[ca1987]

I have gone through 5 CDIs now. I have looked at the stator, it looks brand new; it tests perfect. I cleaned it and it works but nothing has changed. Everything works except voltage goes into the CDI and doesnt come out. I am going to replace the stator because I have replaced everything else. My best guess is somehow something is wrong with the stator that cant be diagnosed and it is frying cdi boxes somehow. If a new stator and cdi dont fix this bike my best guess is it is cursed and im going to have to buy another bike.

 

[crazypj]

Are you doing AC or DC tests?
A CDI will be putting 100~300 volts into ignition coil so your probably dealing with TCI, that will have 12 v to coilYou can probably get onto a British site and fins spec for Honda CG125

 

[ca1987]

The stator puts AC into the CDI the CDI puts DC into the ignition coil.

It is definitely CDI. I had one working for 400 hours before it went out. I think it is the stator. But the stator is putting out the right amount of current. Anyway I am replacing the stator, pickup coil, CDI and ignition coil so there's no way it can't work.

 

[crazypj]

CDI is capacitor discharge, you may need a peak voltage adapter to find out exactly what voltage is going to coil but it will be higher than battery voltage.
If your getting battery voltage at coil that is the reason the CDI units are failing and replacing 'everything' won't cure a faulty or incorrect wiring harness which looks it may be the real problem?

 

[ca1987]

Cant be - my ignition system is seperate from charging/battery/lights. It goes straight from the stator to the CDI.

 

[ca1987]

I replaced the entire ignition system today and have the same issue. Stator, pickup coil, cdi, ignition coil all brand new. Voltage comes from the stator, and from the pickup coil, and goes into the cdi, and nothing (or negative voltage) comes out of it. If anyone has any ideas please help. I am ordering my 6th CDI because I have nothing else I can do and this is my only vehicle.


EDIT: I just found that if I remove the ground(s) from the CDI and crank it, then replace the grounds it will output voltage again but drop as it did before. It should fire if I remove the grounds and charge it. I don't want to have to remove the grounds from my CDI every time I want to start the bike though, and I'm not sure if it will idle once it fires.

EDIT 2: It's still not getting spark. I hit it with my 12v charger and it sparks, but when I hook it up to the CDI after charging it by taking the grounds off (I've tested before and it put out 16v and began to drop slowly) I get no spark. I am out of ideas.

 

[crazypj]

CDI is capacitor discharge, you may need a peak voltage adapter to find out exactly what voltage is going to coil but it will be higher than battery voltage.
If your getting battery voltage at coil that is the reason the CDI units are failing and replacing 'everything' won't cure a faulty or incorrect wiring harness which looks it may be the real problem?

Your a moron if you thing there isn't any other wiring
If you have an ignition switch or kill switch, either the pickup coil will be grounded or the charge coil will ground out to prevent spark and shut off engine

 

[ca1987]

I built this bike I know how the wiring works. There is no other wiring. The kill switch is connected to the CDI and grounds it when flipped. I disconnected it to take it out of the equation. It is stator, pickup coil, cdi, ignition coil. That's it. The lights/battery/key/charging is all on a separate system. Don't post in my thread and call me names. You are not offering any solutions so leave.

 

[Rich Ard]

You're sure the battery is up to snuff? You mention early in the thread that it is not performing under load, and then later that you are able to get good spark on auxiliary power

 

[crazypj]

No one else has a clue, you built it, throwing parts at it isn't helping so you'll have to learn how the stuff works so you can test it
You either have mis-matched parts or something connected backwards.
With all new parts you should still have a spark,the fact you don't says something is wrong

 

[Rich Ard]

No one else has a clue, you built it, throwing parts at it isn't helping so you'll have to learn how the stuff works so you can test it
You either have mis-matched parts or something connected backwards.
With all new parts you should still have a spark,the fact you don't says something is wrong

+1

If you buy a sixth CDI then PJ was right to call names :

 

[mydlyfkryzis]

I built this bike I know how the wiring works. There is no other wiring. The kill switch is connected to the CDI and grounds it when flipped. I disconnected it to take it out of the equation. It is stator, pickup coil, cdi, ignition coil. That's it. The lights/battery/key/charging is all on a separate system.

Then it should work....No wiring issues, 5 sets of parts. If you keep doing the same thing over and over, and expect different results, then you are clinically insane.

You are making the same mistake over and over. Whatever it is...

If you rule out the parts (5 CDi's), then it HAS to be wiring... Only a Kill switch? No wires to the coils? no wires from the CDI pickup to the CDI box? There has to be wires and one or more is either broken but looks good, or has a bad connection, or something...

You need to check the continuity of every wire. Stop replacing and start troubleshooting. I can't help more, since you obviously custom wired the bike so I doubt the OEM schematic would help here.

Good Luck...