Reply To: Norton Big 4 Spark Plugs

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Definitely a 977B. What I can’t be certain of is whether this is the original magneto. Hopefully, as Geoff has a manual for the Norton Big 4 industrial version, this will show the correct mag and illustrate how the timing is carried out. I am trying to avoid taking the mag apart as it has only just been rebuilt and is working perfectly, but if no one has any info on the 977B and how (or even if) the timing can be adjusted, this might be my only course of action.