Racing Ignition Coil 55mm For Aprilia RS 125 Extrema/Replica 2007

If your coil has two wires (primary) and it's not obvious to which way these are connected, do not worry as all our coils are made to fit either way.

Each of the wires are connected to the same coil of wire inside the body of the coil just at opposite ends so it does not matter which way round you connect them.

If you've been told otherwise as plenty of 'experts' will disagree with the above then this is the way to ensure you have the two (primary) wires the correct way round.

Test by hooking up a voltmeter with the negative lead to inside the spark plug cap or HT lead so it's touching metal/carbon inner and the positive lead to a grounding/earth point such as the engine block. Set the meter to the highest voltage and crank the engine over (no need to start it) which should show an upward reading of the voltmeter needle (don't be concerned with the reading). If the needle swings down off the scale, switch round the coil primary wires.

Replacement ignition coils may give resistance readings that are different to genuine ones or from what it may state in your user manual (which are known to be incorrect at times) but this will not always mean a fault. If you need to check a coil look for readings that remain stable, normal rates could read anything between 0.6 and 5.0 ohms (The higher reading typical for classics) for the primary and 6k to 14k ohms (The lower reading typical for classics) for the secondary. Only when ohms readings vary significantly or have no reading the coil can then be classed as faulty. All the secondary resistance does is change the length of time the plug sparks for, so a higher resistance literally just makes the spark stay for longer and we are talking milliseconds.