Is This A Bad CDI or Stator?

Bikeman

New Member
Apr 26, 2011
27
0
0
MS Gulf Coast
I pulled my motor off to paint it the other day. It was running good before I took it off now it won't start. Like not even firing. I have verified I have fuel. The plug is wet and mashing the tickler makes gas come out the air filter like it should. I pedaled back home and looked it over and found I accidently switched the black and blue wires to the CDI! DOH!!!! I put them back and tried again. It will fire only if you pedal real fast before cranking it. Then it just bucks like it's trying to run if you keep the throttle wide open, but will not run without the clutch being engaged. One time it took of for a few seconds like it was going to run and then nothing. I brought it back home checked spark and found it very weak looking with a drill cranking it at full speed. Turning slowly doesn't even spark at all.
Here are my test results......
Cranking voltage out of stator with 1400RPM drill - 36Volts AC
Stator Ohms Blue to Black - 300ohms
CDI Blue to Black Wires - 6.4Megaohms
CDI Plug wire to Blue - 6.4Megaohms
CDI Plug wire to Black - 2.5Kiloohms
The CDI box says 075 stamped on it. This is for a 66CC slant motor. Can someone tell me if these readings indicate a weak stator or just a blown CDI? Will getting the wires crossed cause it to self destruct?
 

Bikeman

New Member
Apr 26, 2011
27
0
0
MS Gulf Coast
Nobody knows? I took a gamble and ordered just oredered the CDI from PirateCycles. Looks just like mine. He said he would guess the CDI because of the reversed wires, but has not had this happen to him.
It makes since that it could fry it because the way it is wired the Black wire is grounded to the motor in the stator housing. The spark from the CDI jumps the plug and returns to ground. Since the CDI is not grounded anywhere except the Black wire, it may have caused problems since it was returning on the Blue wire to the CDI?
 

Ritchie

New Member
May 20, 2008
14
0
0
Manitoba, Canada
I just finished building my first bike, and have no spark. My CDI readings are similar to yours. Blue to Black is 6M Ohm and Plug to blue is also 6M Ohm. My Mag readings are the standard results posted all over this site and it can make a bulb glow when I spin it with a drill.

I'd be interested to know if the new CDI fixed your proble.

-Ritchie.
 

Bikeman

New Member
Apr 26, 2011
27
0
0
MS Gulf Coast
Yes, Ritchie, it was the CDI. I now think that you can't really diagnose the CDI with a multimeter, but you can take output of the magneto. My drill spun it over around 1100RPM's or so and I was getting 36Volts AC, not DC, out of the black and blue wires. Plugging in the CDI and testing again, I only got 26Volts with the bad CDI hooked up. As SOON as I put the new CDI on, the plug was throwing bright blue sparks and I knew it would run judging by how much black unburnt fuel came out of the muffler from pedaling so hard to try to get it to crank last time.
Now you say, you can make a bulb glow, by using the drill. Are you talking about on the WHITE and black wires? I only got 2.6Volts AC out of it spinning it with the drill, so you must be on the black and blue wires to have enough voltage to light a 12V? bulb? Got to have a meter to know for sure. Try taking an old sparkplug and closing the gap REALLY close and hold it against a shiny engine ground and spin it over with the drill again. If you see little tiny sparks, that's what my CDI did too.
 

DaveC

Member
Jul 14, 2010
970
0
16
Boise, ID
There have been reports of the CDI frying from not connecting the spark plug up so I'm not surprised it fries hooked up backwards. My problem with the HT motors has been the stators, don't really know why :p
 

biknut

Well-Known Member
Sep 28, 2010
6,511
207
63
Dallas
I pulled my motor off to paint it the other day. It was running good before I took it off now it won't start. Like not even firing. I have verified I have fuel. The plug is wet and mashing the tickler makes gas come out the air filter like it should. I pedaled back home and looked it over and found I accidently switched the black and blue wires to the CDI! DOH!!!! I put them back and tried again. It will fire only if you pedal real fast before cranking it. Then it just bucks like it's trying to run if you keep the throttle wide open, but will not run without the clutch being engaged. One time it took of for a few seconds like it was going to run and then nothing. I brought it back home checked spark and found it very weak looking with a drill cranking it at full speed. Turning slowly doesn't even spark at all.
Here are my test results......
Cranking voltage out of stator with 1400RPM drill - 36Volts AC
Stator Ohms Blue to Black - 300ohms
CDI Blue to Black Wires - 6.4Megaohms
CDI Plug wire to Blue - 6.4Megaohms
CDI Plug wire to Black - 2.5Kiloohms
The CDI box says 075 stamped on it. This is for a 66CC slant motor. Can someone tell me if these readings indicate a weak stator or just a blown CDI? Will getting the wires crossed cause it to self destruct?
I was checking the voltage on a new SkyHawk 80 yesterday. At idle I was seeing about 50 vac. Reving the motor it got up to 80 vac.

I think your stator sounds good. It's probably the CDI box. That's what I'd try first.