I started a DT3 overhaul a couple of years ago, but had to put that project on the shelf for a while.  I'm finally putting the bike back together.

Unfortunately, after all that time, I've forgotten where some things are supposed to go.  I'm hoping someone will help me out with a couple of fairly simple wiring questions.

I have a photo to post, but I guess that feature isn't available right now.  I'll try to describe the connectors:

From the main harness that passes under the fuel tank, just forward of the wires that go down to the magneto, there are two black ground wires, about six inches long, that are crimped to a single "C" shaped terminal.

If you know where that two-wire ground connector is supposed to be connected, please let me know.

Also, just forward of those two wires is a single, short, black wire with a female bullet connector.  If memory serves, that's a test lead that isn't normally connected to anything.  Do I have that right?

Thanks for your help.

Mark
 

Harness wires under the tank usually has the ground point at the ignition coil mounting bolt.  

I think you are correct on the bullet wire.  

The single Female connector on the main harness is likely for the Hi tension ignition coil .
The spare black female connector for testing , is on the magneto harness .

Thanks for your replies. I found a youtube DT3 restoration video that is turning out to be very helpful:


The guy doesn't show how he installed the wiring, however . . .

1:18:15 - At the bottom right of the picture frame you can see two black wires running parallel in the forward direction.

1:19:06 - A better view of those same wires exiting the loom and leading up to the coil.

1:19:46 - A closer view showing the terminal wire insulation extending from the aft screw of the coil mount.

You were right Mark.

After looking more closely, I realized that the female connector forward of the double ground is for the coil ground.  The test lead is further down stream on the magneto branch as Swoop56 advised. It has a thicker, round plastic socket.

Now if I can just figure out where A-B-C and X-Y-Z go!

Thanks again for your help.

Anyone have any idea when we'll be able to post images? I have a couple of DT diagrams to share when that feature is available again.
 

Some extra advice on grounding. When restoring it is likely that parts get painted or powder coated. If not, they can be rusty or dirty. Make sure that items and wires that need to be grounded are contacting clean, bare metal. Also, at least 1 contact point of the engine crankcase mounting to a frame tab is bare and clean.

The DT3 is my favorite rider. I have 3 that are original and unrestored.

Don't get black from the mag confused with black "in the main loom" [if I'm thinking right] as mag black is the "go wire" for spark. Loom black is earth for everything else. Loom normaly earth's to the coil mount under tank. Mag black should have a female short black branching off it as a 'points breaking' checking wire for checking timing. Happy to be corrected as been a long time.

Thanks for that tip.

I'm the original owner of my DT3.  I still have the dealer's receipt ($813.00 inc. tax) and my Yamaha warranty card.  I'll be passing all of that along to my son, but I'm hoping I'll have a few more years of riding ahead of me.  Hoping.     : )

The ignition coil does not have a ground wire.  It only has one black (or sometimes black/white) wire.  Coil grounds to frame through mounting bolts.  

As was mentioned, common source of confusion is wire from points to coil is black and NOT a ground.  With the exception of the "test wire" on some models, the rest of the black wires should be grounds.

In case nobody mentioned it, you need to use a third party host for photos like Imgur and then link them here.  Direct posting of photos will likely be broken until the site is completely rebuilt with new software.