Dyna S and coil problems

Have a 1978 CB750 with a dyna S ignition. Had no spark on the 2-3 stock coil so I installed new dyna coils with a resistor pack. When I timed the new coils the coils the 1-4 timed correctly but when I went to the 2-3 coil the timing light stays on all the time? Purchased a new set of dyna coils thinking I had burned a coil but still have the same problem. Checked all the wiring and connections multiple times. Any ideas or help on where to go from here

Something about this bike and the Dyna. I can't suggest anything, because I gave up and went back to points. I had the same issue. The Dyna plate grounds to the system with a charge, so you can't really time it that way. I did tests that Dyna suggested to see if my sensors were bad. The test showed bad, so I replaced them. Then, the new one showed bad with the same test. Now I have an extra Dyna. Worked my meter all the way back to the field coil. Changed out the field coil. Turns out, the field coil when tested off the bike is actually good. The Dyna gives you the impression that the charging system is bad. They draw power and you have to get to like 5k rpms to get it to charge right. I'm sure guys have gotten them to work, but a lot of guys hate them on the 77-78 750's. I, for one, will stick to standard points from now on.

The problem I ran into with my Dyna S was that the slots drilled in the plate didn't allow adequate adjustment on one set of cylinders (I believe it was 2/3 but it's been about 6 or 7 years since I did this), in other words was severely retarding spark timing. If I recall correctly I think I had to drill the plate out a little bit in order to set the timing correctly.

We use Dyna S on our race CB160s with total loss systems (no charging circuit) and they do tend to suck the electrons out of the battery. On the GT750 systems with 3 pickups, they can eat a battery alive if the revs are not kept up high enough to balance the current draw. We only destroyed one pickup in a decade or two and that was when it was grossly overheated on a motor that was eating itself and turning everything an amazing shade of blue.

A simple way to check if a module is working is to remove the rotor and put it back on backwards and simply rotate the rotor with your fingers. As the magnet in the rotor passes the module it should make nice blue sparks at the coil or should turn the test light ON.

Those coils are double ended and both sides must be grounded through a spark plug or tester.

^^ That actually makes sense. I tried flipping the plate and no good. It was definitely showing signs of being retarded timing, especially on 1/4 for mine. Fouling the hell out of plugs.