I need an electrical diagram for my 2005 quad sport 400 4whlr.

SOURCE: charge-run wiring diagram 1982 Yamaha 650 4 cly & 76 Kaw 750 twin

1982 yamaha 650 maxim coil problem

SOURCE: need wire diagram for the turn signal switch.

your wires are crossed/shorting somewhere, probably in the headlight. remove the light to get to all the wires. you should be able to see which colors go to which side, also look at the wires coming from the turn signals both front and rear lefts will be same color and the rights will be another color. you should be able to tell by looking inside the switch which side is which color and which one is the feed to the switch

SOURCE: I'm installing a new rear tail light with turn

use a light pen that you can get from auto parts store to find the hot wires for l and r sides

SOURCE: Honda VT500EF, 1983-1988, flasher unit wiring.

The flasher unit is made to flash 12 volts on and off only. The turn signal switch is what is used to direct that flashing 12 volts to the proper signals.
The flasher unit:
First wire is a ground. Middle wire is the send to the turn signal switch. The last wire is 12v positive (with key on). When you flip the switch to the left, it makes a connection between the left turn signals and the middle wire of the flasher unit. The flasher unit then "sees' a load and starts flashing 12v on and off at the middle wire. When you flip the switch right, it makes the connection between the right signals and the middle wire of the flasher unit. Again, the flasher unit "sees" a load and starts flashing.

SOURCE: Looking for a wiring diagram for a Yamaha BWS 50

The service manual has a diagram, but you need to zoom in to read the colors.
You can download a free one at
http://www.yamaha-motor-europe.com/community/service/manuals.jsp
Good luck!