1986 Honda VT 500 C Shadow tail light not working

SOURCE: both brake lights do not work

try changing the bulbs

SOURCE: Valve specs for VT 500 honda shadow 1983

Hi,
Your valve clearances should be:
Intake .08-.12 mm (.003-.005 in)
Exhaust .12-.16 mm (.005-.006 in)
I usually start all gaps in the middle of given specs, then fine tune from there.
Hope this helps

SOURCE: I need to bleed the clutch on my vt 700 shadow, 1986 model

My guess is that unless it leaked out, your master or slave cylinder is going out. But I assume you must have already checked the reservoir to see if it has any brake fluid in it. So crack open that bleeder valve down there at the slave cylinder and let it drip while you keep the res. full. When you stop seeing air bubbles, close the bleeder and top off fluid. Great Job!

SOURCE: 1984 Honda Shadow VT700 Taillight/All other rear lights out.

it be a bad ground connection to the bikes frame or a bad ignition switch

SOURCE: tail lights of my honda accord are not working, brake are working

CHANGE OUT THE SOCKETS THE BULBS GO IN AND CHECK THE FUSES ALSO GOOD LUCK!