Hi I am a new member just having picked up  a 1977 DT400. Engine is good but guage sand lights aren't great. It also has no papers so getting it street legal on Canada as it is may be difficult even if I got electrical and some new parts added. As I just drive off-road I am thinking of stripping lights and gushes and going with single killswitch. I don't drive at night. Strictly a fun field bike for ripping around the cottage and back trails. Has anyone done this to a DT to make it more like a MX. can the whole electrical wiring harness and battery be taken off as well with just a kill switch added? Thanks for any help.

I'm familiar with yamaha wiring from work starting in the early1960's, so i'm old--very old haha therefore see what others say.
But--black/white from the cdi box will be your kill switch so with the stator plugged to the box all you have to worry about is the orange color to the plug coil direct then away ya go.
Without looking--i'll research later tonight-- but if there's a black plus a black-white out of the box then joining those through a kill switch will stop it by earthing the source coil internally in the box back through 'that' black to the stator plate.
Motor is earthed to the frame so i don't think it'd matter if you just earthing the black/white through kill switch to the frame mount for the plug coil under the tank.
Whatever is easiest, so long as motor mounts are tight, & the top rear by memory is a bonded rubber mount so important the other 3 are tight or she'll vibrate worse than normal.
Man i complicate things, sorry about that. Cheers from NZ & Welcome.
ps, here's my old 360 trail rat bike first start after a long hibernation & all flooded up. Needs a damn good thrashing to clear it out haha so better get too it.
Goes like like a rocket on a good day.
Be good to have a pic of your beast sometime but i think you need a certain amount of post before you can link pics.
Don't think you can direct load pics from your computer & has to come via an external whatever ya call them.
I'm using google photos for pics but i'm out of free storage although my video is from youtube of course.
You're allowed to laugh at the bike.
I just remembered i'm waiting for the clutch to explode from machining to take some old good plates out of something,
Maybe my old yz465 or yz490 back in the "80's
photos.app.goo.gl/KnzC1vpLsHA4eB3L7

www.youtube.com/shorts/I6ZMtvCIhWc
 

Thanks for your reply and your advice. Love your bike. Can't beat old air cooled 2 strokes. New Zealand is on my wife and my bucket list. Definitely want to visit. Co workers went 2x and loved it. Cheers