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Yep, Brian hit it on the head. There are two pickup coils under the timing cover. Each one fires one coil (well, the TCI fires the coil but from the signal it gets from the pickup coil.). Each time a pick up coil gives the signal to the TCI it signals the corresponding coil that it has matched to that pickup coil to send the voltage to both spark plugs it controls, one is firing on compression stroke the other just sparks with no result. Thus the term "wasted spark". And as a side note, the system needs both wires hooked to plugs or at least grounded to the engine to fire EITHER spark plug. So if you say, forget to reattach a plug wire after doing some service on the machine and try to drive it, the plug wire can flop around in the breeze occasionally grounding to the engine which will make the bike fluctuate between running on two cylinders or three.
..DAMHIKIJK.
It is not all that uncommon for someone to pull the pickup coils off and put them back on 180 degress reversed. The TCI don't care which coil it is firing, it just sends the signal to the coil that matches the pickup it got the signal from. Thats the only way it knows when to send spark.
As Brian stated, the wires that run from the TCI to the coils are in pairs one has a red and orange wire, the other a red and grey wire. The plugs are identical and can easily be swapped. Which, again the TCI don't care, it just sends the spark to the wires that match the pickup that signaled, if it is the wrong coil or not.
HTH
..DAMHIKIJK.It is not all that uncommon for someone to pull the pickup coils off and put them back on 180 degress reversed. The TCI don't care which coil it is firing, it just sends the signal to the coil that matches the pickup it got the signal from. Thats the only way it knows when to send spark.
As Brian stated, the wires that run from the TCI to the coils are in pairs one has a red and orange wire, the other a red and grey wire. The plugs are identical and can easily be swapped. Which, again the TCI don't care, it just sends the spark to the wires that match the pickup that signaled, if it is the wrong coil or not.
HTH
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