Honda xr signal LED lights not flashing - 1998 Honda XR 400R

Sounds like a short like the insulation on wire rubbed off. Could also be a loose connection on either the hot or ground side of light circuit. This would blow a fuse.

I would assume this is to make bike road legal
To add turn signals You can add some signal relays and wire up to battery and a switch so each time you turn for left or right it triggers relay which triggers the light ..

if the turn signal worked before try to change the wires to the led, make sure the positive is on the correct wire to the led.(switch them)
Also make sure fuse to turn signal is still good.

Only problem I have heard of is the speed that the led indicators flash at. May be too fast to pass MOT. This is solved by changing the flasher relay for one made for led lights or fitting resistors in the wires to indicators which sometimes are included with the led lights.

reset the lamp timer. unplug it and plug it back in. hold down the enter, down, and menu buttons, then press the power button.

remove stock relay ,find out which is live in on the new ic relay and connect this to the blue wire,find the live output from the relay and connect this to the grey wire, the last wire may need to be connected to ground to provide an ground signal to make it flash.