81' CB650 won't Spark

[tibbon]

I picked up an '81 CB650 from a guy recently for almost nothing. Looks to be in great shape, but he didn't have it running at the time.

Anyway, I can't get the bike to spark.

The starter turns over. I've checked the ignition coils by trying them on another CB650, same with the spark generator. I measured the pulse generator with my multimeter and it was exactly to spec (and looked in great condition). I've tried putting a new set of plugs in. Checked several cables for shorts. No fuses blown or getting hot. I've tried to use contact cleaner on everything I can find to spray it on. The plug wirings look in ok shape and I'd find it suspect for all four of them to be bad. The battery is new and I've charged it fully.

My ONLY guess that I have left is that the right hand kill switch thinks that its constantly in the 'off' position and thus will allow no spark. Going to try to remove and open up the assembly later and test it.

Any other ideas? There aren't that many other parts that could be bad aside from some random wiring mishap somewhere deep in the bike that I haven't been able to trace yet.

[tibbon]

I just throughly cleaned and tested the right hand killswitch. Seems to check out just fine. I am absolutely positively out of ideas for why it might not be sparking.

[Custom82Hawk]

well, you could always try a new wire harness.  or perhaps a used one from another bike.  your local salvage yard (if you have one) or fleabay may help.  i'd say though, if you've replaced the plugs, still having issues, try replacing the wires.  won't hurt anything....

[Bumblebee]

If they're original, don't be surprised if all 4 spark wires are dead. If push comes to shove you can check for spark at the coil terminals without spark plug wires.

Do you have the wiring diagram for the bike?
You can chase the lack of volts backward from the coils all the way to the pulse generator fairly easily.
Start following the volts or lack thereof.

[tibbon]

I suppose I could just check the continuity of the spark wires themselves (I haven't yet). I could probably pull two of them temporarily from my '79 CM400T to try to see if I can get spark on those ones too.

I've got 12V incoming at the coils. Should probably pull out my scope to see if they are actually getting pulses and changes in signal when I'm trying to fire. If this comes down to four faulty spark wires I'm going to laugh sadly at myself for some time here. I do have the wiring diagram and the shop manual. There's a diagram at http://www.myhonda650.com/images/cb650wiring.jpg which matches what is in my book.

[tibbon]

I went out to do some more testing this morning and found that the battery is suddenly drained. This seems to indicate (to me) that there is some short somewhere. No fuses are blowing, but there's something slowly draining the battery. Once this is recharged i'm going back out there and finding out how much current is being pulled and try to trace where it is coming from. I figure it I can find what is drawing current- then I'm likely to find the short.

Hopefully this is related to my ignition problems and not just another red herring.