Two questions:

1) the directions say to connect the Red from the regulator to a yellow wire that you find near where the ignition coil is located (they seem to be assuming I connected the regulator in that area), can I not just connect it to the yellow wire that came off of the old 6 volt regulator? I did mount the new 12 volt regulator where the original 6 volt was located. Here's a copy of their directions...

"Also at this location find the Yellow wire and connect the red wire from the new regulator. This supplies the power to the entire system. This is labeled “D” on the diagram.;

2) The directions say "When you removed the old system, a white plastic connector that was connected to the old stator is left on the harness just under the oil tank. It is labeled "C" on the diagram. Make up a connector/leads that connect all 3 wires together. This will jump all the power to all the systems on the bike." I have a white plastic connector that has two wires but not three, could this be it?

Thanks for any help!

I'd love to help... could you post pictures of the wires you're thinking of connecting to?

What year/model is this?

There are a few ways that will work.

Good morning Mark and thanks for the help! My bike is a 76 DT400.

This first picture is of the yellow wire that originally connected to the factory regulator.

This second picture is of the white connector that only has two connections rather than the three the instructions talked about.

Here's a screen shot of the instructions for connecting the yellow wire to regulator:

Here's the instructions for the white connector:

Nice pictures, thanks.

Here's what you can do:

Option 1: Connect Red from new regulator to the Yamaha harness Yellow and Green/red at your white plastic connector. Then you don't connect anything to the yellow that went to the original Yamaha regulator.

Option 2: Connect Red from new regulator to the Yellow that went to the original regulator. Then install a jumper wire across the Yellow and Green/red at the white plastic connector to connect them together. You already have two little jumper wires coming out of the plastic plug so you could just connect them together. Easy peasy.

Note that the wiring diagram shows the 2 wires at the white plastic plug to be Yellow and Green/red... it looks like your green could be solid green? That's fine. The Yellow and green in that plug need to be connected together in option 2 or both to the red if you find option 1 easier. (Seems like option 2 would be easiest?)

For the kill wire, you want to connect the B/W to the original CDI to the Powerdynamo kill wire... (blue?) Sometimes the clean way to do this is connect the B/W to the B at the CDI box connectors. Then you can connect the Powerdynamo kill wire to the B which went to the original ignition coil. (Hope that makes sense... if you want to do this post a pic of your original CDI box connections and I will try to identify the wires... according to the wiring diagram the B to the original coil is alone.)



Last thing is the original rectifier. What does Powerdynamo say about that? Often they say to remove it. You may not want to.

The green/red (or green) is the battery charge wire. It connects to a white which goes to one side of the original rectifier. The red coming out of the rectifier goes to the battery to charge it.

The rectifier is a one-way valve that (crudely) turns the AC from the original green to DC by only letting the "+" voltage get to the battery.

The Powerdynamo red is already DC power so technically you don't need to use the Yamaha rectifier to convert AC to DC.

The thing is you've now "jumped" what were originally two separate circuits... yellow and green together. Without the original rectifier, the battery will "backfeed" to the yellow circuit and power the headlight even with the engine and key off. So you'll always have to remember to use the headlight switch to turn the headlight off.

If you leave the original rectifier in place, it acts as a "one way" valve which allows the battery to charge with the engine running but prevents the battery from backfeeding the yellow headlight circuit. So with original rectifier left in place, headlight will only come on with engine running and headlight switch on... just like original.

Rectifier Option 1: Remove (connect red and white together) and headlight with run off battery at any time... key on or off... engine running or not... controlled only by the on-off switch on left handlebar.

Rectifier Option 2: Leave original rectifier in place and headlight will work the same way as stock. Only with engine running and controlled by on-off switch on left handlebar.

P.S. Some notes on the rectifier for different models...

On the early models, the headlight on-off is controlled by the key switch so removing the original rectifier will allow the headlight to remain on with engine off... but at least when you shut the key off the headlight is off.

On the later models... 1978 on?... by US law there is no longer a headlight on-off switch. If you remove the stock rectifier you will need to install an on-off switch for the headlight or it will be on all the time... at least until the battery goes dead. Leaving the original rectifier in place on these models is clearly the best option.

Hey Mark, Thank you very much!!! That was a well written explanation and made complete sense to a non electrical person like me. I like option two and will go with that. As for the rectifier, they said to remove it and connect the wires together, that's what I did so will leave it at that for now. For the kill wire, I connected the blue from the powerdynamo to the BW wire as the instructions called for, I used a wire tap for that.

Thanks again!
Tony

Option 2 is what I'd do.

With the rectifier removed, just be aware that the headlight on-off switch will always be live... so you have to remember to turn switch off and/or if you have kids or something you might want to disconnect the battery when parked so it doesn't get ruined by someone turning on the headlight and running the battery completely dead.

Hey Mark, got everything connected up and kicked her over, and over and over and over... I pulled the plug which was dry (I just rebuilt the carb too), so I sprayed a little brake cleaner in the hole, installed the plug and went to kick it again, glanced at the kill switch and son of a gun, it was off clicked it to run and she fired right up idles great at 1500.

Only problem now is the damn battery that was supposed to fit from the information I got doesn't allow the seat to close! I'm thinking I should just connect the system up to run without battery, what do ya think?

Thanks for all your help, I was hesitant to do this because I'm not real great at wiring but you helped big time!