Ignition Question - Again!

[Keithh]

Hello all. Yes, I'm back with more info to ponder as I try to get Pycho Bike (the possessed 79 Standard) to run consistantly. The main pattern that I seem to be noticing is that when it decides to run, it runs great! Had it out last Sunday for an 80 mile run, never missed a beat - ran great. Put it away in the garage, two days later - no spark! This pattern has happened before, where after a good run, it has problems starting (it doesn't) on the next attempt.

Just as background info - it has a new (expensive) battery; charging system works (puts out 14.5 volts while running), I changed the whole harness; I have removed all items from the circuits that have nothing to do ignition/starting. Using kick start doesn't solve the problem. I can't think of anything that hasn't been checked a dozen times already. Handlebar switches, e-stop switch, connections cleaned, etc.

Now, doing some troubleshooting and taking some readings, I find the following: When checking the voltage atthe coils, red and white: 12 volts or more. When checking the voltage on the trigger side - orange and grey wires, I found that taking the voltage reading at the grey wire while cranking, the voltage drops from 12 to around 10 or so. Running the same check on the orange wire while cranking, the voltage drops to 2 volts or less. The coils seem to check out fine (the two from the bike and two spares pretty much read the same ohms) - changing them out makes on difference. When I switch coils to see if the problem moves, it doesn't. The orange wire from the TCI still reads 2 volts or so. This has me baffled! What can make one leg of the trigger wires read so much different? I checked the ohms to the pick up coils and both are the same, so no good explaination for the difference at the coils. I tried the spare TCI (known good) and all remains the same.

Any thoughts on this only the latest info? Once again, the guys with the white coats are coming for me!

As always, any advice greatly appreciated!

Cheers to all

Keith

[bikerphil]

Do you still have the original old style glass fuses in there or have you upgraded to the blade type yet?

[CaptonZap]

It would seem that if the components being changed doesn't effect the outcome, then the problem would be in the wiring.
Jumper the orange wire between the TCI and the coil and see what happens.
A safety pin stuck through the wire, at the terminal, will get you close enough. (That is assuming that you have given the terminal connecters a CLOSE visual inspection, and all is in order).
Disconnect the wiring plugs at both ends and check the orange and grey wires for resistence, and possible partial ground.
And are you sure that the spare TCI is good?
CZ

[Keithh]

Thanks for the info - I do have blade type fuses (got the box from TC) and the TCI was recently serviced and tested by DaVinci. I tried it as well and it appeared to work fine. I'm thinking wire as well, but why wouldn't the other coil fire??? I'm still looking for a breaker points conversion for the XS11!

[Gallaecus]

unscrew your plug caps, cut a 1/4 inch off the spark plug wires and screw the caps back on....cant hurt....worth a shot...

while you got the caps off....check your resistance, and the resistance of just the caps...

primary is about 1.5 ohms
secondary is about 15 K ohms ....less without the caps....

[Keithh]

Thanks - I'll give it a shot - can't hurt!!!

[natemoen]

That is 15k without the caps and 25k with the 2 5k caps.

[Gallaecus]

That is 15k without the caps and 25k with the 2 5k caps.

the book said 15K with a diagram of caps ON ....but last time i checked mine
I had 12 k without caps
and 2 and 3 caps (longer) were 8 k
and 1 and 4 caps (shorter) were 5 k

and the bike ran pretty good too.... sooo

[Gallaecus]

That is 15k without the caps and 25k with the 2 5k caps.

is the manual wrong ? I had closer to your values Nate.
they are 81 coils with 3 ohms.

[natemoen]

I think it is just a poor diagram. They probably show the plug boots so people know it is the coils in the pic or something stupid like that.

[GLoweVA]

Now, doing some troubleshooting and taking some readings, I find the following: When checking the voltage atthe coils, red and white: 12 volts or more. When checking the voltage on the trigger side - orange and grey wires, I found that taking the voltage reading at the grey wire while cranking, the voltage drops from 12 to around 10 or so. Running the same check on the orange wire while cranking, the voltage drops to 2 volts or less. The coils seem to check out fine (the two from the bike and two spares pretty much read the same ohms) - changing them out makes on difference. When I switch coils to see if the problem moves, it doesn't. The orange wire from the TCI still reads 2 volts or so. This has me baffled! What can make one leg of the trigger wires read so much different? I checked the ohms to the pick up coils and both are the same, so no good explaination for the difference at the coils. I tried the spare TCI (known good) and all remains the same.


Keith

Keith, I just got a chance to read this thread. There's definitely something amiss here. Those readings for the grey and orange wires should be about the same.
What happens is when the pick up coil 'fires' then the TCI stops the current thru the coil to ground thus causing the coil to fire the spark.
This should be happening equally between the 2.

I would check the continuity of the orange and grey wires from the coils back to the TCI.

You're getting the 12+Volts on the R/W wire during starting so the ballast bypass is working.

It sounds like the coils are okay too. (you swapped them out)

It's still a mystery as to why you still don't get spark some of the time though.

This pic might help.