Working on fitting a Vape kit to my 1978 DT250. Solved the ignition side of the wiring but ran into something on the 12v power side. Vape's instruction reference a DT400B wiring diagram with CDI. The instruction have a step to jumper three wires together on the main harness right where the old stator connected. When I look at the DT400B drawing it looks like it may be different wires than what I have on my DT250. Vape hasnt been able to give me any info unfortunately. I cant post pics here so I can provide links to the instructions and different drawings only. 

Here under the link "original circuit diagram of the DT400" is the diagram they reference. Note the red jumper just past the connector marked "C".
Site is removing the link here. Can either check Vape site instructions or reference the drawings in the tech library. 

The drawing for the 1978 DT250 located in the tech files here shows a different set of wires at that location. Where as the DT400 wires travel only to the headlight switch, the DT250 wires in that location travel to the rectifier, coil, and regulator/power circuit. It seems like if I were to jump the three wires together on my DT250, it would ground the power circuit anytime the kill switch is engaged. Thanks in advance for any help. 


 

You need to have about a dozen posts before you can post links.  Site owner did this due to spammers joining and posting a bunch of spam posts.

I worked with the original owner of Powerdynamo/VAPE on developing some of these systems for the Yamaha Enduros and have installed quite a few of them. I can't find the diagram on the VAPE website you are referring to.  

The "connect 3 wires together" sounds like the instructions I've given on this forum and not something that came from VAPE?  I would like to find the page you're referencing.

On the 1978 DT250, you had a points magneto (at least the US model did, if you still have the original system, I might be interested in buying it)

The stator plug has 4 wires.  

Sky (light) blue is for the oil level sensor and is left alone.

Black/white goes to ignition coil.  It could be connected to the VAPE ignition coil blue "kill" wire but it's easier to connect to the wire the original ignition coil plugged into.  If you're not connecting to VAPE blue here, tape it up.  (If you are connecting blue here, tape up the wire to the original ignition coil.)

Now you have two wires left at the original stator connection.  Yellow (headlight) and Green/white (battery charge) More on connecting these down below.

It's important for me to say here that my "power side" instructions probably vary significantly from what VAPE has.  You have to follow either what I'm saying or what they are saying...  do not "mix" instructions or you could have a mess.  

First point is in 1978 (assuming US model) you do not have a headlight switch.  This is a problem with using the VAPE instructions I've seen because you'd need to add a switch or relay for the headlight or it will stay on all the time!  (At least until the battery dies). Here is my method of wiring to avoid the need for a headlight on-off switch.

Step 1.  Remove the stock voltage regulator.  It's a small box with one yellow wire coming out of it and possibly a black ground wire to one of the two mounting bolts.  It's by the battery on that model if I remember correctly.  Unplug, unbolt, and remove.  

Step 2.  Leave the stock rectifier wired in place.  It is under the gas tank and normally has a white wire and a red wire to it.  Spade connectors on the later models.  (Leaving the rectifier will allow you to have the headlight come on automatically with engine running just like it did originally.)

Step 3.  Connect the Red from the new VAPE regulator/rectifier to both the Yellow and Green/white at the original stator plug.  (Do not connect directly to battery as VAPE might say)

Step 4.  Connect the Brown from the new VAPE regulator/rectifier to a solid chassis ground.  Also ground the case of the new VAPE regulator/rectifier by bolting it to a good chassis ground and/or running a ground wire to the terminal provided on the case.

And of course make sure you have changed battery, bulbs, and turn signal flasher (get a two wire!) to 12v.  (6v horn normally works fine but can also be changed)

If you follow the above instructions, the electrical system will work as it did stock.  Battery components come on with key and headlight comes on when engine is running.  

Hope this helps.

One more point is the stock rectifier is cheap and readily available if yours is questionable.  If you use my method and bypass the rectifier per the VAPE instructions, headlight will be on all the time.  

You could add an on-off switch to the headlight or wire a relay to the key switch to operate the headlight if you want to go that route.  Simply leaving the stock rectifier (aka diode) and connecting the VAPE red as I've described seems to be a more elegant solution to me and I've been doing it for years...  but to each his own.

Amazing information. Thank you so much. As far as selling my old points ignition, I would be happy to. However, the previous owner somehow managed to crack the casting of the stator plate and I believe the rotor and stators made contact at some point. Would be happy to send pics if you would still be interested. Southern US. 

Would I be able to direct message you with those links or are they blocked there as well? If you go to vapes site, search DT250, select the DC version($381) and click the link the says "show complete information" there will be some literature there. Modified DT400B diagram is there. The factory diagram for the 78 DT250 is in the tech library here. 

Adding notes here for what I have done so far:

• The sky blue neutral now bypasses that OEM connector. 
• All lights are removed and i have the new 12V bulbs, battery and flasher relay. 
• The black/white is tied into the Vape coil kill circuit near the original coil mounting location. This was the primary concern that caught my attention where they say to jumper all together as thats ground and the others are positive. Assuming I should be able to remove the black/white from the OEM connector up or at least tape it up as you mentioned? 
• The two leftover wires are yellow(power) and white. The yellow wire is tied into the red of the Vape regulator further up in the harness. Basically where the old regulator tied in. The white is directly into the old rectifier. I did remove this already and will most likely add a relay for a switch for the headlight. Assuming these wires (yellow/white) are both part of the same 12v positive circuit, should I just connect them together?
• I do not have a green/white wire leaving the old stator. 

Really just dont want to destroy the new Vape regulator. 

Diagram said green/white.  But white makes sense because it does in fact go directly to the rectifier on the 1978 model.  

If you follow my directions and leave the rectifier in place, you won't need a relay for the headlight and the added complication and wiring you'll have to add.  

If you don't leave the rectifier in place, then connect the rectifier red and white together and you might as well not connect the yellow to the VAPE red as the output from your relay will power the yellow....  or you'll have to put a switch/relay in the yellow someplace.  

Don't forget to remove the stock voltage regulator!!!! (I didn't see that in your list)

Update after finding the VAPE diagram which was actually at the old Powerdynamo site and reading your post again.    

The white (I originally said green/white) at the stator must connect to the VAPE red.  That white goes to the rectifier which connects to the battery red.  

If you're going to complicate the system by adding (unnecessary) relays and/or switches and wires, then there are many other ways to connect.  

Basically you need to connect the VAPE regulator/rectifier red to the battery (add a fuse if you go directly to the battery).  Then you need to rig up your relay/switch with battery power to power the yellow when the switch or relay is on.

If you leave the stock rectifier in place as I described, all you need to do is connect the VAPE regulator/rectifier red to the yellow and white where the original stator plugged in.  (If you already connected VAPE red to yellow someplace else, then you can simply connect white and yellow together at stator plug.)

Rectifier is a diode (one way switch) and will prevent the battery from "backfeeding" the yellow headlight wire with engine off.  But with engine running it will allow the VAPE regulator output to power the battery.  

Black/white at stator plug can be left in the stock plug as long as it doesn't connect to anything and can't touch a ground point.  Or tape it up if you removed it.

Got it. I'll put the rectifier back in and jump the white and yellow together at the plug. Black/White will get trimmed back in the harness. I'll send you those pics shortly. Thanks again.