can anyone tell me how to test my ignition system? the coil ,stator and cdi not sure where the problem is !

 

First, you wanna check continuity to your ignition coil, this is the small box looking thing that is usually mounted under the fuel tank It will have the main lead going to the spark plug, the other wires will likely be power, ground and kill switch . So to test your primary you wanna set your multi meter to ohms, usually the 20 or 200 setting.. Test from the main where you plug in your spark plug, to the ground wire, then write down your reading, if nothing or OL, you have a bad coil or short. Then to test the secondary winding you test the power wire and the ground, the small wires. These are your primary and secondary windings to ignition coil but if all checks out, refer to manual for proper ohm readings for correct resistance.

If all checks out, proceed to your CDI box, the black box mounted on your frame usually on the neck of the bike where your front wheel and triple clamps connect. Test these from wire to wire, locate the ground which should be a black/yellow with a round connector. The other black/w wire is for kill switch. Test each of the other wires to the ground and measure resistance across the board and compare to manual to make sure is all good, if you get any false or OL readings, your CDI is likely bad. These will go out with no warning, sometimes from getting too hot, other times from looking at it the wrong way, they just do.

If it all checks out good and still no spark you can proceed to your exciter and pickup coils, these will be in the crankcase on the magneto side of the bike. Remove the cover and take off the flywheel/magneto with a flywheel puller, make sure to be careful as you can short out an excited or pickup by grounding out any part of it, so ve careful. After removing the flywheel, find the proper ohm resistance readings from the manual and compare them. Start with the pickup coil, white/red and white/green, test those and that will tell you if your pickup is good. If all checks out, proceed to check the exciter coil winding,, this will be the red/black and red or sometimes orange wire, they fade so sometimes they are more red than orange or vice versa, but you get the point. Test those and compare to the manual, if these all check out and you still are not getting spark, this will mean you have a grounding issue which is easily fixed by making sure your ground contacts are meeting the frame in solid contact, sometimes a small paint chip can be all thats in the way of getting a good contact for your ground... I will sometimes just find point of contact and sand it down real good, look for any rust or material that could be impeding solid connection with your frame.

This is all you need to know about the entire ignition system on a 1991 kx250 with a CDI (Capacitor discharge ignition) or can also be known as a thyristor ignition type.