Hi there, copper strap is for another application ,and connects to the condenser screw that is not grounded . one of the primary ( skinny ) wires of the coil connect there also , along with the " kill " wire ( wire that is to be grounded to stop engine.) other coil primary (skinny ) wire goes to ground . does not matter which one as it is an a.c. magneto word of advice , please do yourself a favor and keep spark plug gaps to a minimum ,,,( suggest .015 making the spark jump long gaps taxes the integrity of the insulation of the magneto coil and these things are hard to find . keep both plug wires hooked up at all times while the motor is turning , as there is no + or - to the system , ( A. C. magneto ) original servicycle points had wire to condenser . Patience pays off with these things , all the best Larry.