Hi guys, I have just swapped a STOP switch to a killcord on my late 80's Mariner 8HP (for sale, check out the for sale bit of the forum if interested). I thought I'd share my conversion. This isn't a hard job and doesn't require you to be electrically minded, though it may help if you have more complex ignition systems.
I removed my STOP switch and changed it for a general killswitch with killcord available from eBay or other places (link at the bottom). It was fairly simple. Unfortunately I only have pictures of the finished article.
1. Remove the existing switch, there is usually a nut inside. This requires some elbow grease or a spanner, the latter being easier as I found out.
2. Cut the two wires (yellow and black in my case) and remove the old switch and nut.
3. Crimp on two female crimp connectors (switch dependent, mine had crimp terminals)
4. Connect the switch up using the contacts that close the circuit (The "C" terminals on the switch I used) and test the switch to make sure it works.
5. Install the switch into the hole (not as easy as it sounds) and screw the nuts on as far as you can.
6. Enjoy having more safety on your RIB/SIB/Boat.
MARINE ATV 12V UNIVERSAL KILL SWITCH BRAND NEW | eBay
Engine was a late 80's Mariner 8HP.