Author Topic: Bad cdi? (Read 2146 times)

Waynerd · « **on:** June 02, 2014, 09:19:45 AM »

So I list spark a while back. Finally got service manual in April. Ohmed out everything yesterday and all is good but trying to ohm coil circuit(bl/y wire) and meter doesn't even read. Does this mean cdi is bad? Dumb question probably but just want to make sure I'm not missing something. Thinking maybe pin not contacting inside cdi or circuit broken somewhere inside it. So should I buy a cdi?

Pumashine · « **Reply #1 on:** June 02, 2014, 09:39:27 AM »

The CDI cannot be tested. They sometimes work intermittently. We suggest swapping it out with a known good one too see if thats the real problem. But having a buddy with a CDI is not always easy to have.

Waynerd · « **Reply #2 on:** June 02, 2014, 09:57:52 AM »

Might be able to find one to borrow. I tried checking resistance between 2 wires that go to coil and the meter reads same as it does when it's not connected to anything. I'm assuming that this is the max resistance. Service manual states .1-.3 ohms I think so this would mean the cucuit is broken somewhere. It's not the ground because I tried several and they worked for the other circuits.

DnB_Racing · « **Reply #3 on:** June 02, 2014, 07:09:35 PM »

Quote from: Waynerd;35602

Might be able to find one to borrow. I tried checking resistance between 2 wires that go to coil and the meter reads same as it does when it's not connected to anything. I'm assuming that this is the max resistance. Service manual states .1-.3 ohms I think so this would mean the cucuit is broken somewhere. It's not the ground because I tried several and they worked for the other circuits.

the coil should have very little to NO resistance 0.1 to 0.3 just the opposite of what your saying(not "max resistance")
this reading is reading the windings in the coil and should be almost like a dead short ... as all your reading is a single wire wound up,
its like touching the meter leads together only a slight resistance added for the additional length, if your not reading any thing or as you say max resistance then you have an open or high resistance coil winding ,
and will not get spark

if your really reading blk/yellow to ground and getting the MINIMUM resistance to ground the coil is good!!!

. ether its going to ground with little resistance and the coil is good, or its bad and reading high resistance

please clarify what your findings were, and we can see what your real problem is and help you fix it

what does your secondary side of your coil read to ground?

Waynerd · « **Reply #4 on:** June 02, 2014, 07:39:24 PM »

Sorry if I made it sound confusing. Coil primary and secondary are both reading in spec. I was testing the wires coming out of the cdi witch the manual states should be .1-.3 but mine is reading max. This tells me that somewhere within the cdi the circuit is either shorted or disconnected. Again the blk/y wire from cdi that goes to coil not the coil itself. Does anyone know of any other reason y this would happen or is it just a bad cdi?

DnB_Racing · « **Reply #5 on:** June 02, 2014, 08:28:35 PM »

Quote from: Waynerd;35639

Sorry if I made it sound confusing. Coil primary and secondary are both reading in spec. I was testing the wires coming out of the cdi witch the manual states should be .1-.3 but mine is reading max. This tells me that somewhere within the cdi the circuit is either shorted or disconnected. Again the blk/y wire from cdi that goes to coil not the coil itself. Does anyone know of any other reason y this would happen or is it just a bad cdi?

the .1 to.3 are the coil readings at the cdi connector from coil not cdi,

you cant test cdi with any accuracy,

inside the cdi......depending on the charge of the capacitor the scr might not have any readings, along with the scr being polarity sensitive, makes any cdi readings a guess at any level of solid state and capacitive knowledge... too many variables inside the cdi ,

something as simple as changing the polarity of your test leads will yield different results, you would need to know the proper range to measure the farads or micro farads of the capacitor and at what point of the gate that the scr is in at that test point to be able to get any type of measurement and that wont tell you much, only that the caps will take a charge..
all this to say you cant test a cdi with any accuracy

I would look at all your connections, look for any discoloring of the plastic to indicate heat, or resistance, along with plug wire cap cut back about 1/4 inch to get to the good center conductor with the cap, make sure your kill switch and key are free from any corrosion and water
then I would make sure the flywheel key is good and not all rusted along with making sure your flywheel magnets aren't loose
then if still nothing try swapping out your cdi with a know good

Waynerd · « **Reply #6 on:** June 02, 2014, 08:49:08 PM »

Exactly why I came on here to ask. Apparently I misunderstood the manual. That's why I wasn't sure because I know the capacitor doesn't discharge until it is signaled by the pulse generator so I didn't think that circuit should always have almost no resistance. Like I said the stator tested fine but I have read elsewhere that the stator might test ok but still be bad. Guess my next step will be pulling the flywheel. There was some corrosion inside cover when I pulled it. Another thing not sure if it matters but the blk/rd wire from stator lights a test light and blk/w wires from cdi that go to key and bar switches also lights test light. Have been doing my testing with the blk/w wires not connected to switches thereby eliminating any bad switches.