Hi all, recently bought a vape system for my 75 DT400. Flywheel/stator is in and timed and Im getting spark but I can’t figure out how to patch into the lighting system. Here is what I have so far.
new coil yellow, brown and red to stator, blue to blk/wht in harness
regulator red to battery positive, brown to batt negative, base to ground, two black to stator
rectifier red and wht jumped
harness under oil tank wht and yellow/wht jumped
originsl CDI disconnected. Includes brown, wht/red, blk. Wht/grn, org, blk, blk/wht
orig regulator wht/yel disconnected

bike runs but no lights and I don’t know how to patch in. Could really use some advice. 

R=regulated 12V by VAPE

R->G/R ; (CHARGE- LIGHT SW ON) Sends power to WHITE -> RECTIFIER -> Fuse -> Battery
R->G/W: (CHARGE- LIGHT SW OFF)sends power to WHITE -> RECTIFIER -> Fuse -> Battery
R->Y: (POWER FOR HEADLIGHT/GAUGES) sends power to Y headlight circuit (dimmer sw).
Brown (from Vape) -> Ground  ;  Note Yamaha oEM brown wire is POWER from keyswitch.
Blue -> Blk/White; test this circuit before start up!

I currently have the original rectifier in mine. Like a free switch to cut voltage in reverse. I tested jumped and works both ways.

Oh gosh! That’s a lot! Thank you for taking the time to reply. I’ll sit with this and try to understand. Do I splice into the red to one of the original yellow connections to get power into the lights, horn and turn indicators? 

The following are BATTERY POWERED via IGNITION SWITCH

TURN INDICATORS:
Under the tank, on clutch side you will see a BROWN wire and a BROWN/WHITE wire. The brown wire is switched battery power. The turn signal flasher generally lives in that area. The outgoing pulsed power goes to the BROWN/WHITE back to the handle bar switch selector. 

HORN: 
Pink: Ground via push button
Brown: key switched power from battery.

TAIL LIGHT: 
Blue: power when lights are "switched" on. source is battery; brake light should work independent of tail light switch on or not.
Black: ground

The VAPE sends AC power to the regulator/rectifier combo box via those 2 black wires, then outputs 12V DC to the red wire.
If you connect that red to the YELLOW, you will have headlight power. 

BTW, there is a service manual in the tech section that indicates wire schematic and colors.   

You can find several posts I've written over the years on the theory and details of wiring the VAPE (aka Powerdynamo)

Abbreviated version:

Disconnect the original 6v voltage regulator if you have one.

Red from new VAPE regulator to the Yellow, and both greens (Possibly yellow/white, green/red, and green/white? I don't remember the stripe colors, if any, for the 75 off hand) that the ORIGINAL stator connected to.   Those wires should be in a white plastic connector right where the original CDI wires plugged in to stator (if harness is original). 

Note:  do not run the VAPE red directly to the battery.

I'd leave the original rectifier in place.

Alternatively, you can connect the original rectifier red and white together but then headlight will run off battery whenever headlight switch is on.  

Thanks so much both of you for clarifying. I got voluntold this weekend and it’s raining here in the SF northbay so may not be able to dig in for a few days but I’m excited to apply your advice. Seriously thank you for the help!