Spark/Coils/TCI

[geneborg]

'80XS11LG Have been having a spark issue that I thought that I had resolved. Had not started the bike is a few months. Tried the other day and again no spark. May have done the same thing last time inadvertently and ended up doing the same thing again and got spark. At the TCI I got almost 11 volts at both the orange and gray wires but when cranking got ~10 volts on the gray but only got ~3 on the orange wire. Also still no spark. Swapped TCI's and got the same readings. Also same readings at the coils for the same wires. I disconnected the orange wire at the coil and now got spark on the gray coil or #s 2 & 3. Swapped the gray wire to the orange coil wire and got spark. My thinking being to see if the coil was bad??? The black and white wire to the coils has voltage. I then rewired the orange and gay wires correctly and now have spark on all four again.
Does the TCI have to have both coils working correctly to have spark on all four? If something is amiss with one coil or its wiring, does that affect the TCI and the spark on both coils.
Why do I not get spark and then when doing my switching around with the orange and gray wires now get spark? Am I clearing a bad connection or some how affect a marginal coil to make it work until it sits awhile.
I will also see if I still have spark after sitting over night?
gene in FL Where the summers are hot and the humidity reallly high.

[CaptonZap]

The TCI has two strings of transistors, each string handling one coil, from pick up signal to coil switching. If one side quits working, USUALLY, the other side keeps on keeping on.
The electricity flows through the wht/red wire to the coils, and then to the TCI, which makes and breaks the flow through the coils to ground, which creates the spark. The fact that you got three volts at the orange coil wire indicates that there is a resistance in the primary circuit of that coil. Did you measure ohms through the primary? Check all the connections for cleanliness and good mechanical contact.
The fact that it is a sporadic fault hints that it is an internal fault with the coil. They tend to fail that way. And without some sophisticated test equipment with which to measure a lot of internal parameters, the best bet is to substitute a known good coil and try again.

CZ

[CaptonZap]

. The fact that you got three volts at the orange coil wire indicates that there is a resistance in the primary circuit of that coil. Did you measure ohms through the primary? Check all the connections for cleanliness and good mechanical contact.

CZ

Let me clarify that somewhat.
That statement holds if there is a current flow through that circuit. If there is no current flow, you should read input voltage (12 V). Was that measurement made with the TCI connector on or off? If off, you might have a primary coil winding open that has enough carbon tracking to pass three volts through the carbon and the current draw of the meter. (Which is REALLY small)
A good visual inspection of all connectors in that circuit is in order.

CZ

[motoman]

'80XS11LG Have been having a spark issue that I thought that I had resolved. Had not started the bike is a few months. Tried the other day and again no spark. May have done the same thing last time inadvertently and ended up doing the same thing again and got spark. At the TCI I got almost 11 volts at both the orange and gray wires but when cranking got ~10 volts on the gray but only got ~3 on the orange wire. Also still no spark. Swapped TCI's and got the same readings. Also same readings at the coils for the same wires. I disconnected the orange wire at the coil and now got spark on the gray coil or #s 2 & 3. Swapped the gray wire to the orange coil wire and got spark. My thinking being to see if the coil was bad??? The black and white wire to the coils has voltage. I then rewired the orange and gay wires correctly and now have spark on all four again.
Does the TCI have to have both coils working correctly to have spark on all four? If something is amiss with one coil or its wiring, does that affect the TCI and the spark on both coils.
Why do I not get spark and then when doing my switching around with the orange and gray wires now get spark? Am I clearing a bad connection or some how affect a marginal coil to make it work until it sits awhile.
I will also see if I still have spark after sitting over night?
gene in FL Where the summers are hot and the humidity reallly high.

In short, you NEED 12volts at primary side of both coils.......carry on my friend.

[DiverRay]

As a thought, I just replaced the coils in my Quail bike. When I put the bike together, both coils measured good with a meter BEFORE I installed them. I've been having problems with the running, and have tried everything else. I ordered a pair of VF1000R Honda coils off ebay, and last night when I pulled the old coils out, one was open!

[dbeardslee]

I don't have a lot of faith in the stock coils. Part of the problem is that the high tension wires are permanently attached, and after thirty-plus years they can get pretty brittle. When I replaced the coils on my '79 F I thought I'd keep the old coils. When I went to put them in a three pound coffee can I had to bend the high tension wires to get them in the can, and they snapped clean in two! You can put new high tension wires in old coils, but it's kind of a PITA, and they still will only output 15Kv. I much prefer 30Kv Dyna coils.

Another problem with those old high tension wires is that you can get voltage leakage through the insulation. If they're touching the motor they can even short out.

As far as the 11v at the TCI - that can be an indication of corroded terminals. When I redid the electrical connections on Betsy I kept checking the voltage at the TCI as I crimped new terminals. I'd get a tenth of a volt here, and two tenths of a volt there, and next thing I new I was up to full voltage at the TCI. If you haven't redone your electrical connectors, you might want to think about it.

[motoman]

I don't have a lot of faith in the stock coils. Part of the problem is that the high tension wires are permanently attached, and after thirty-plus years they can get pretty brittle. When I replaced the coils on my '79 F I thought I'd keep the old coils. When I went to put them in a three pound coffee can I had to bend the high tension wires to get them in the can, and they snapped clean in two! You can put new high tension wires in old coils, but it's kind of a PITA, and they still will only output 15Kv. I much prefer 30Kv Dyna coils.

Another problem with those old high tension wires is that you can get voltage leakage through the insulation. If they're touching the motor they can even short out.

As far as the 11v at the TCI - that can be an indication of corroded terminals. When I redid the electrical connections on Betsy I kept checking the voltage at the TCI as I crimped new terminals. I'd get a tenth of a volt here, and two tenths of a volt there, and next thing I new I was up to full voltage at the TCI. If you haven't redone your electrical connectors, you might want to think about it.

Problem is they are epoxy filled coils for heat dissapation and after many years of heating cooling cycle the epoxy cracks internally giving partial unloaded spark an easy route of least resistance to ground.