You can download the owner's manual for the '86 Fourtrax 250 at the link below. It has a wiring diagram in the back, but it's a little hard to read the colors of the wires.
http://campaigns.hondampe.com.au/Motorcycles/manuals/atv/own86trx250.pdf
It looks like there's a couple optional wires back near the taillights.
http://campaigns.hondampe.com.au/Motorcycles/manuals/atv/own86trx250.pdf
It looks like there's a couple optional wires back near the taillights.