No you don't need one, its just handy for turning the engine off.
first, take your sparkplug out and disconect the kill switch wires (just the ones for the kill) and crank the engine over (you want spark)...if that doesn't work then, you need to hard-wire the 2 wires together that are for your kill switch
most of the time it would b wired so the spark gets grounded before it goes to the CDI (off position), but in some it is the opposite
Now you haveto choke it to turn her off
'85 ATC 250R
FMF Fatty & Power Core
Boyesen Rad Valve
38 PWK A/S
K&N w/PF (next purchase)
LSR +4 Axcaliber axle
LSR Duel row bearing carrier
DuraBlue Anti-fade (to be installed)
13/36 sprockets
'85 ATC 250R
Parts trike (maybe future build?)