Parts needed:
ZX14, ZG1400, ZX10 Stick coils and coil harness. Others will fit but I have yet to use them
(4) 1/4" male spade crimp on connectors.
Good tape. Scotch #33 or similiar
Soldering iron and solder
This is basically how it's done. Wire them in series like you would for 2 12v batteries in a diesel truck.
The stock zx14 harness has almost all the colors there so try to use them that way. When prepping the zx connectors, cut them leaving the longest tails possible on the coil connectors!!! It's easier to see in the first pic below the #2-#3 coil plug conns(the 2 that are wired closer together)You have a red lead and a BLK/GRN striped colored lead loose. Then the negative(black or green) from the first connector gets soldered to the positive on the second connector. I use a black magic marker to color in the #1-#4 negative lead solid, some harnesses will leave you with a WHT/BLU wire for that. I usually only have to solder 2 or 3 connections. 3 if the one red lead isn't long enough. There will be plenty of red wire leftover to add to the short one.
Her's for the #1-#4 coils
1/4" male spade connectors installed. Available at Radioshack etc
This shows the stock ZX grommet down in the hole just a tad. These will seal this way just fine I believe.
Roughly where the rubber grommet gets slid down the stick coil to
With the stock zl grommet trimmed and put over the zx grommet. I'll bet someone could find a better solution.