How to test a coil.

step one, remove plug cap

step two, wet finger tip

step three, hold HT lead in hand with wet finger tip 10mm away from lead end

step 4, get freind, brother or sister to kick said NSR over.

If the coils have enough whack in them to make you "clucking bell" their ok.

On a more sensible note, if you have a faint spark i would be looking at the coil pick ups, coil connectors and like Andy said the batt.
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If I have to take the carbs off once more...