spark problems NEED HELP

[jimmy5090]

Im working on a 81 stock motor with new coil and homemade wiring harness. The motor is in a motor stand and i have just the motor wired(none of the accessories). When i turn the key from off to on i get a single spark. when i turn the key all the way to start i get no spark. I have tried two sets of keyed ignitions. The battery is full charged and i have checked the wiring diagram many times to make sure my wires are correct(which i still may have something crossed) I have also tried two different used reg/rec, not sure if that could have anything to do with the problem. Does anyone know what it causing the problem?

 

[gggGary]

It has a TCI and pickups? Test both by the repair manual.
The TCI needs to be grounded to work. Doesn't matter that you no longer have the stock harness, the wires connect the pieces the same way. (or they should anyways).

 

[xjwmx]

Are you sure the TCI's getting power when the key is in the start pos? It would seem to be when it's in the on pos, although I don't know why it sparks there one time. How do you have the on and start wired so that on doesn't fire the starter? Did you overlook power to the tci in start pos?

 

[jimmy5090]

thanks guys for the info i used the 1981 simplified and complete wiring diagram posted by inxs in the tech section i will double check everything tonight and get back to you. the start is wired just like inxs diagram. im not sure if that answers your question. i will test the tci and pickups tonight thanks

 

[xjwmx]

When i turn the key from off to on i get a single spark. when i turn the key all the way to start i get no spark.

I'm assuming your starter motor is there and when you turn the key all the way to start, the starter motor is supposed to run? No diagram that I glanced for just now has that. Does the starter motor run? If you don't have a starter motor, why do you have an on position plus a start position?

 

[Grinder]

Just to clarify, are you using an automotive type ignition switch and if so how many terminals are on the back? Where do you have the wires going to on the switch? Some stock XS switches have a second position on them that is used as a park feature where only the tail light comes on.

 

[jimmy5090]

xj i have a starter and it does turn over when i turn the key to start but when it turns the motor i dont get spark, only when i switch from off to on do i get one single spark. grinder i have two different brand new automotive switches one has three terminals and the other one has four the one with four has accessorry but i am not using that terminal. thanks guys for the help

 

[jimmy5090]

would it matter what gauge i am using? all the new wire is 14 gauge. it just doesnt make sense i am getting spark from off to on but not to start. how do i check power to the tci?

 

[xjwmx]

how do i check power to the tci?

You would go back to the schematic you used, and follow the leads of the tci until you find the one that goes to 12v. Then make sure it's there in both key postions. In your test setup, do you have the motor grounded to the battery neg?

Try this - put it in the on position, then jump the starter solenoid to run it for a sec and see if it tries to start and if you get good spark.

 

[jimmy5090]

when i jump the starter solenoid it blows the fuse should i just use wire with out fuse to jump it i have the battery grounded to the engine stand(frame) do i need to ground it directly to the motor?

 

[xjwmx]

when i jump the starter solenoid it blows the fuse should i just use wire with out fuse to jump it i have the battery grounded to the engine stand(frame) do i need to ground it directly to the motor?

Don't eliminate the fuse. Figure out why it's blowing. It shouldn't.

The ground to the engine is okay. As long as there's a current path from the battery neg to the engine it's good enough.

If you can get spark going this way, it'll tell you something about the igntion switch wiring is wrong. If you can't, it might imply the pickup or it's connection is bad, assuming the tci is getting power and ground. You should have checked power and ground to the tci already. Check its ground the same way I suggested to check its power.

 

[jimmy5090]

so i rewired my bike last night thinking i would fix the spark problem but it does the extact same thing. im thinking about putting new diodes in the tci anyone think this might help fix the problem? any other suggestions?

 

[jimmy5090]

help please

 

[xjwmx]

I think you're shooting in the dark and about ready to hit your foot.

Try this. Take your ignition switch loose. Then go back to the schematic you used and wire the 'on' and 'start' exactly as in the schematic for the moment. For the 'on' switch twist two wires together, and for the start button, touch two wires together briefly. Get it working that way first, because I think the problem is in how you've wired that ignition switch. There may be more to it too, but it's got to be figured out systematically. We'll eliminate the complication of that switch to start with.

 

[jimmy5090]

i will give it a try tonight and let you know how it goes. thanks for helping me out

 

[jimmy5090]

so i have been working on the frame and put the motor on hold but now im back to the motor. i have checked positive and negative to the tci and they are both around 25 and the battery is around 27. i pulled the ignition switch and tried starting it with no switch got the same thing (spark only when i first touch the wires together) any other suggestions?

 

[hmusket]

Maybe you can post some pictures of your setup? Your wiring diagram? It might help.

 

[jimmy5090]

im using the 1981 simplified and complete wiring diagram posted in the "some wiring diagrams" by inxs. my set up is a rats nest its just to get the motor running not for final assembly so a pic would probably not help you guys much. i checked the rotor between the two slip rings and i got 1.2 so that means my rotor is bad. when chekcing the rotor do you put the digital meter on ohms 200? i get subtracting the original reading from the final reading. which means i really have 1.0. im using a greenlee digital multimeter. would that cause the spark problem? i know it will cause charging problems down the road but i just want spark right now not worried about the rotor unless it is causing all the problems.

 

[gggGary]

so i have been working on the frame and put the motor on hold but now im back to the motor. i have checked positive and negative to the tci and they are both around 25

25 what?????

and the battery is around 27

27 what???

Check your ground wires. spark occurs when the voltage is removed. So my guess is you have a bad connection somewhere when you hook up the wire it GROUNDS the coil and collapses the field so it sparks. disconnect the TCI from the coil ground that coil wire when you remove the ground it should spark. Trust nothing use a 12 volt bulb to check for voltage AND currant at the TCI wires and the coil hot and ground.

 

[gggGary]

Is your coil bolted to the motor? It has to be grounded to the motor and battery.