zxr 750 1991 spark issue!

[RickTaff]

Replaced coil pack about month and a half back and bike was running on all 4 cylinders

Haven't touched the bike since, its been sat under a cover, but tested the coils again using a spark checking tool - as planning to take it for MOT next week, and I now have spark in cylinder 1 and 4, but nothing in 2 and 3

Coil pack 1 goes to cylinder 1 and 4, pack 2 goes to cylinder 2 and 3

So swapped the coils around and again 1 and 4 sparked, 2 and 3 didnt. So i know the coil packs are fine

A mate who was helping me suggested it could be a faulty pickup coil, but if that was fucked would it not cause all 4 cylinders to show no spark? I am stumped, only thing which has changed since it was running on all 4 cylinders, is the battery will have drained somewhat as it hasn't had a charge (charging as we speak though)

[jaffa90]

Have you a wiring diagram ? You may have 2 trigger coils 180 degrees apart.

[RickTaff]

[Nobby the Bastard]

Bad wire from the ignition or no earth from the coil on the lt side.

Most likely bad earth.


On the outside chance it's the ignition black box the easiest way to check is to borrow a known good one.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050