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!

I recently installed a Vape on my 76, and just installed a Rex on to a 75.

For the Vape on the 76 I jumpered the black/black white in the unused old 3 pin rubber chassis CDI connector to get the kill switches working. Both the 75 and 76 have w black wires here, you want the one that is male on the chassis side. Verify with your meter though. The other goes to chassis ground.

Then for the lighting side I installed the Vape reg/rect where the stock 76 regulator went. The black AC wires to it was easy, then where it tied in to the bike, crimped 2 wires in to the red vape regulator terminal, its a 6.3mm or 1/4" female disconnect and plugged that in to the yellow wire on the white plastic chassis side lighting harness terminal connector. Then the spare wire I crimped in to the terminal went to the white wire in the same connector. Left the rectifier plugged in like MarkT suggests. Everything works as expected

Though I do not get great charging voltage with the headlight on at low RPM, maybe this is to be expected. 8v running at idle headlight on, 13v headlight off. Perhaps MarkT could give me some feed back here. I expected better. I havent dug in to it because the bike came apart shortly after to send the top end out to get ported and head work, and the trans was making a growl.

The 75 is a little bit different. There is a yellow white, a green red, and a green white. I have no clue what the green white one actually does. The rex kit only uses 2 of these terminals, in its connector and I do not know which because that connector was cut off of my harness. Its obviously the yellow and one of the greens. I traced the white and green back to the lighting switch connector, and it dead ends right there. I am not sure if my lighting switch or the harness there is wrong, or if that wire was used in the Euro spec lighting/key switch set up. So this leads me to believe it is the green/red that needs power on the 75 with the vape, but it probably cant hurt to jumper them all like I did. This bike is scattered in parts all over the garage with the cases split so I cant really test anything currently. Just trying to get ahead.

The 76 bike omits they yellow white and the switch functions differently as a result.


Where are you in the North Bay? I am near Fairfield and may be able to help if you have issues, or maybe we could swap some parts if we have spares the other needs. I am not a big fan of crossing any bridges though.

Great info! I’m in Glen Ellen near Sonoma. I’m wondering now if I have a 76. The oil tank says otherwise but I only have a yellow and white in the white plastic connnector which originally connected to the stator. I’m curious about the battery connection. Everything you said makes sense except where the battery comes in. I have the brown from the regulator going to the battery negative and the red from the regulator going to the battery positive as vape suggested. 
 

Nvm. I just realized I needed to connect the battery to the original connection. That was the missing piece. Put back in the rectifier and reconnected. Red from regulator split to yellow and white in harness under oil tank. All working great. It screams but it has a weird lope at low idle. Maybe timing is slightly off. Thanks all for the advice. This group has always been so awesome.