View Full Version : No Spark!!!!! Help

06-28-2014, 7:59 PM
Alright i just finished wiring up my sportster build with a bare bones wiring harness/ diagram. It turns and turns and cranks but no spark at all... Got plugs and wires and still nothing.... So im guessing next on the list of back tracking would be the coil. Im using the stock 1990 coil, that worked great when i took it off in march. I am also using the stock ignition module that also worked great in march when the build began. Here is the wiring diagram i went off of. See any problems? Does the polarity of the wires connecting to the coil play a role??? Could a quick swap of them be the answer?? I try super hard to do this wiring not half assed so i dont think it would be a wire problem. Anything helps guys thanks.


06-28-2014, 9:18 PM
Let's start with the basics. Do u have 12v to the coil + with ignition on? Do u have a good ground. Ohm it out from bat - to point where coil grounds to frame or engine. Then to the coil. U can ohm out coil. Should be a spec on line to tell u if coil is good

06-28-2014, 9:28 PM
Sorry. Brain fart. The neg did of coil goes to ign mod. U won't b able to ohm it out. Make sure ign mod has a good ground. Run a temp wire right to bat - if needed to rule out bad ground

06-29-2014, 8:58 AM
That temp hot wire will also help if the switch your running kills power to the acc circuit while "start" is engaged.
Also a starter can drag voltage down enough that the ignition won't spark, esp with a weak batt and/or a sumped crankcase (from sitting since march).
You can pull the spark plugs while spinning the motor to help clear out the oil if you think it needs it.

06-29-2014, 9:32 AM
just did this the other day dude. what year bike? are you using stock cdi? wire colors to module on your diagram don't look right. here is 2 stock wiring for a cdi simplfied..........