Help please anyone with a understanding of BSA electrics

[Dig8599]

Hi everyone
I have a 1966 A65 Lightening ,it was put away 4 ish months ago running,however now it has no spark and I cannot work it out,It has been converted to electronic ignition and has a Wassell MK2 ignition unit on it,The black wire from the unit goes to one of the coil terminals, The red wire from the ignition unit has 12 volts coming from it and it goes to the coil but it also branches off and goes to a frame earth,if I test for power at the coil with the frame earth connected I get nothing at all,If I disconnect the frame earth, then I get 12 volts at the coil but still no spark at the plugs,I am happy to replace valves,cams and pistons all day long, BUT I have a limited understanding of electrics and BSA electrics seem to defy logic,All and any help gratefully received.
Kindest regards
Steve

[Catz]

Is it a new or old battery? Is it fully charged?

[cornishbob]

check that earth wire. has it got power running through it? earth it somewhere else. check the earth from the battery.
is there a fuse there?

i almost had a baby (and ive had the snip) when i saw how my boyer was wired in.

i just checked every wire twice. i did find that the fitting at the coil was loose on mine. cocked the earthing right up

just remember i know more about quantum physics than BSA electrics

[Dig8599]

It was heavy duty jump leads off of my van battery to the terminals,Van not running and battery live disconnected from van,Lights turn on bright and horn working well on bike,plenty of power there, however I have noticed that the brake light comes on as soon as I switch the ignition on, so I pulled the two wires out of the brake light switch and it still comes on, Not sure how or why that is occuring ! My instinct is to assume a short somewhere.

[cornishbob]

is that the REAR light or the BRAKE light thats on all the time? the bikes not damp (wet) is it? got a gentle heater you can have blow on it a bit

just thinking