Do ignition coils need to be earthed?

[Ian ParkinParticipant @ianparkin39383]

On my bmw r100 that I’m rebuilding I’ve cleaned and repainted teh ignition coils and brackets..

do i need a sound earth to the outer can?  Should i scratch away the fresh paint and put a lead in and clamp it in the bracket and terminate that to a earth point?

[Speedy Builder5Participant @speedybuilder5]

No unless BMW have a special system, but two coils in series is strange. I couldn’t see the rest of the diagram and can only assume that the green circuit goes to earth via the contact breaker/electronic ignition.

[bernard towersParticipant @bernardtowers37738]

Not necessary.

[Ian ParkinParticipant @ianparkin39383]

Speedy

here’s the rest of the diagram

the green is live +12v the brown from the ICU is ground

[mgnbukParticipant @mgnbuk]

but two coils in series is strange

2 x 6v coils in series for wasted spark on a twin with a single trigger – originally a single set of points, electronic trigger + amplifier on “post ’81” models as show. Japanese bikes that used a wasted spark system used a single coil unit with two HT leads to get the same effect.

Coil cases are isolated.

Pretty reliable systems – my wife’s similarly equipped ’86 registered (but ’84 built)  R65LS is still running all it’s original parts apart from the trigger unit. And the trigger unit was a self-inflicted error on my part – the face drive dog for the trigger that fits in the end of the camshaft  is offset & I managed to put it together the wrong way round – it didn’t like that long-term ! Still worked electronically but IIRC the bearingsin the can wore . Coming up on 100K miles now

Nigel B.

[JAParticipant @ja]

Wipac – 1959.

JA

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