Topic: Plugs spark when starter button is released

[Scott S]

 Working on a 550F that came to me with NO electrical components other than a Dyna ignition.

 I gathered up the correct F model wiring harness, a set of coils from my stash, etc. I found a set of controls that were supposed to cross reference but some of the wiring was slightly different. I was able to figure the wiring and now I have headlight HI/LO, tail and brake light, horn, starter button works, engine spins until oil light goes out, etc. Still have a little work to do n turn signals, but I can figure that out.

 But when I tried to test for spark, I don't see any spark until the moment that I release the starter button. No spark when cranking the engine.

 Talked to CalJ briefly yesterday and he gave me a few tests to try:

 Key off. No continuity on YELLOW/RED wire that goes to starter solenoid.
 
 Key off. Hit starter button. Show continuity on Y/R.

 No voltage to Y/R no matter what, with it unplugged. Plug it back in and starter works. That indicates that the Y/R is a ground on this bike.

 Cal suspects a bad Dyna. I guess the Dyna stores some energy and is known to discharge when the bike is turned off?

 Does this sound correct? Is there anything else I can check to see why I don't get spark when cranking the engine but show a spark when I release the starter button?

[69cb750]

The newer bikes with no headlight switch turn the lights off when pressing starter button, if coils are connected to this circuit this would happen.
Check for spark using kick starter.
Or buy a points plate and check again.

[calj737]

That indicates that the Y/R is a powered circuit on this bike.

FTFY

[Scott S]

That indicates that the Y/R is a powered circuit on this bike.

FTFY

 I copied the text you sent me yesterday. So the Y/R is a powered circuit?


 And the "cuts headlight when button is pushed"..... that might be a hint. I do know there is a mystery wire that goes to the starter button and I thought I figured out it was somehow related to the headlight circuit. I mentioned that in a different thread I have on figuring out the wiring harness.  Let me see if I can find that....

[Scott S]

 Maybe there's a hint in here?

http://forums.sohc4.net/index.php/topic,177074.0.html

[seanbarney41]

I would suspect a borderline low voltage at the coils...so when the starter motor is sucking down a bunch of voltage there is not enough left over for the ignition.  Try a spark test just using the kicker?  I know that usually requires more than 2 hands.

[TwoTired]

What the?  The coils are powered by the key switch and STOP-RUN-STOP switch, not the starter button...  How else could you kick start it?

The starter button only provides power to headlight OR the starter solenoid.


Yes the dyna-s  sparks when power removed.  That's been reported before. 

You've got mis-wires to trace.

[Scott S]

 Just a follow up here.

 Moved the BLACK/BROWN wire off of the headlight fuse connector and to BLACK, got spark!

 First, I tried just leaving it disconnected, as the stock wiring harness only shows the wires for the headlight fuse and the starter solenoid going to the starter button. But that got me nothing at all....not even a spark when releasing the button.
 On a hunch, I tried connecting it to BLACK and it all works as it should now!