Hi, i noticed that after i ride my bike the battery is not being charged but rather discharged, so i checked the voltage across the battery terminals and it turned out to be around 17-18V, and my guess is that the reg/rec is faulty but when i checked for newer one or second hand, most of the reg/rec's had only 5 pins, while the nc21 uses 2 connectors (one with 3 pins and one with 4). The yellow wires are clear, but how do i manage the 2 green and 2 red/white (not sure of the color) if I buy a 5 pin reg/rec? Couldn't find a solution in the search bar. Help because next week the season opens up in my town and i dont want my bike to stop because of the battery

If charge voltage has been 17-18 volts then the battery may be suspect also. Your multimeter should show a short between the two green wires from the rect/reg and another short between the two red/white wires from the rect/reg. Two green wires can be connected together and two red/white can also be connected together, to make one green and one red/white wire pair.

As above... the battery might already have been killed charging it at that that high voltage.

5 pin regulator is fine to use... the 3 yellows go in any order and just join the two reds together to make 1 red and the two greens to make 1 green.

make sure you solder the connections with good spade connectors.. if you just crimp them they will corrode and burn.

Thank you for the reply!