250sx Spark help????

[3wheelernoobie]

Hello again guys
Okay here's the problem, btw I'm fully aware of the search bar but I can't find anyone else who has had this problem, so here it goes . I just bought my first three wheeler and on my first ride I've fallen in love, but after taking the bike home and under further examination the wiring on this bike was completely jerry rigged . The switch didn't work and you had to jump it off at the solenoid . I went ahead and fixed all the lose connections and installed a new switch, I pushed the button and nothing the bike wouldn't start, it was getting gas and air but for some reason wasn't sparking . I broke out my test light and found I was getting power to both sides of the coil and yet It wasn't sparking, I put a new spark plug on it and same thing. I know the stator is good and the pickup coil is good because it ran like a champ before re did the wiring. Is the coil ment to be getting power to both sides? Or may I have a loose ground that I don't know about ? Any way guys any help would be amazingly appreciated. I want to get to riding this asap, :) as I said I'm in love may never ride a four wheeler again.

[3wheelernoobie]

Bump ! I really need this help.

[250sxman]

Check to make sure your coil plug (where the coil wire fits onto the plug) has plenty of wire to bite on. I had this issue on a 200s once. If that's not the case, then check all grounds, or better yet, re-do them. Trace them all down, make sure they have a good, clean, unpainted spot on the frame, and make sure they are tight. You may also want to check the switch you installed to make sure it's in working order.

Double check everything you have done. Think of it this way, (and this is not a dig at your three wheeler mechanic skills) it WAS running before you worked on it, so chances are you may have missed something or got something in the wrong order. It happens.

250SX's are great machines, (my favorite) and will last a long time if they are kept up. And if you haven't already, check the gear oil in your rear end, and change the fluid. Chances are it hasn't been done in a while. Good luck.

[3wheelernoobie]

One question though, is the coil ment to be getting power to both sides when I hit the button ?

[Flyingw]

First of all, its helpful to understand how the electrical system works. This helps you to troubleshoot problems. The electrical system is divided up in to five groups.

Ignition
Starter
Lighting
Charging
Ground

All five systems are independent of each other.

Ignition System
The ignition system on all trikes is AC based. Thats why the book referrs to the stator as an alternator. As the flywheel spins, the magnets in the flywheel spin past the exciter coil and induces an AC voltage which is sent down the wires to the CDI. There is a capacitor in the CDI that stores that AC voltage. There is also a small magnet on the outside of the flywheel that passes by the pickup coil. When the magnet passes by the pickup coil, it induces a tiny voltage in to the pickup coil which is sent to the CDI telling it to discharge the stored AC voltage in the capacitor. That AC voltage is sent to the primary side of the ignition coil where it is stepped up to about 40,000 volts in the secondary side of the ignition coil which is what the spark plug needs to fire the motor.

Ground
The main wiring harness is grounded on the frame on the left side of the tail by the battery box. Ensure that grounding point is clean and tight. The coils that make up the stator (exciter & lighting) are grounded to the engine case. The engine case is grounded to the frame, battery ground is connected to the case as well, and the wiring harness is connected to the frame mechanically connecting all the grounds together. Ground is everything. No ground, no electrical.

Starter System
The starter system is a fairly simple circuit. It uses battery power to turn the starter. The starter solenoid gets it power from the battery. Positive power is always sitting on the solenoid. The control for the solenoid is via a ground that comes from the switch screwed in to the bottom of the clutch cover. When the motor is is neutral, a contact mounted to the shift drum contacts the clutch cover switch and provides a ground to the other side of the starter solenoid thus enabling the starter system. This also turns on the neutral light on the dash. This is why the trike has to be in neutral for the electric starter to work. There is also another switch for the reverse light. You can put the trike in neutral and with a meter read continuity between the tap on the neutral switch and frame ground. Same for reverse when the tranny is in reverse.

Lighting/Charging System
The lighting system works much the same as the ignition system in that the flywheel spins, induces an AC voltage in to the lighting coil and the output is an AC voltage. The voltage is connected to the regulator. The regulator is actually an inverter/regulator. The lighting on the SX is powered with AC voltage. Because AC power generation is variable depending on engine RPMS (12vac-50vac), the regulator puts a 13.6vac cap on the output voltage to prevent the light bulbs from blowing. Coming out of the regulator is also a tap that goes to the battery to recharge the battery. That voltage is processed through an inverter in the regulator which changes AC voltage to DC voltage to charge the battery.

So thats it in a nutshell. To answer your question about the coil, no...... There is two blade connectors on the primary of the ignition coil. There is one side typically marked with green marker. That is the ground side. Be sure the green wire is connected to the green blade of the ignition coil. The other side is positive. For the coil to work you must have ground and positive power. If you have a manual, the manual gives resistance readings for checking the primary and secondary of the ignition coil.

The kill switch works by grounding out the storage capacitor in the CDI preventing it from charging even if the motor is spinning.

Get the book and check all the electrical parts listed in the manual. It tells you what you need to know to accomplish this. The CDI is not checkable with a meter because its fully transistorized and requires special gizmos to check it. If all the parts, exciter coil, pickup coil, ignition coil, wiring, and ground all check good per the book then I would be looking at replacing the CDI.

[3wheelernoobie]

i can not thank you enough for your help, now I know my exact problem. Atlest I think, Im allways looking to expand my knowledge. I appreciate your help with any luck my problem will be solved tomorrow. :)

[Flyingw]

Thats why we're here Brother. Just shout if you need any help.