Hello all,
I'm new here and this is my first post, so apologies in advance-

I recently traded a friend for a 1976 Yamaha DT250 that is in need of a total restoration. It seems like it sat outside for a lot of years and was worked on by someone who never should've had access to wire cutters. It is missing the entire wiring harness, but fortunately still has the points and condenser as well as the generator still intact. It had an ignition switch, but it doesn't seem to be for this model as it does not match any of the wiring diagrams I have seen.

My questions boil down to this: First, am I correct in assuming that the wiring harness for the '76 DT250 is the same as the harness for the '75? Second, does anyone have experience building a DT250 wiring harness from scratch? I have built a wiring harness for a CT90 before but I am much more familiar with those bikes, and I had a complete harness on hand to reference at the time. Third, would it be possible (or easier) to make a wiring harness for a '68 DT1 and fit it to my bike? I downloaded the appropriate wiring diagrams from the technical library and I like that the '68 is color coded and seemingly simpler.

Thanks for your time! I look forward to getting this old bike back on the road, but it is going to be a very long journey.

 from near Salisbury, UK.

Pretty sure that the 1975 DT250 harness will fit your bike. The only difference that I can think of is that the '76 might have been wired for a voltage regulator and the '75 not - this is easily overcome, though.

Have you checked fleabay, Arsebook marketplace etc for a decent used one?

DEET on this forum makes new harnesses for some models.

Looks like the part number for your main switch is 443-82508-21. CMSNL have one for sale, as well as a couple of photos of it. They also list which other models used it, so you can widen your search to include those as well.

 

Contact DEET. He makes new harnesses that are very high quality

Greetings from Tennessee. 

Thanks for the responses! It seems like buying a harness from DEET is the best choice. I have checked fleabay and all of the harnesses I have seen are either not even close or shipped directly from China, which in my experience is a definite no-go. Has anyone just rigged a temporary harness to hear it run? I don't want to sink a lot into this bike until I am 100% sure it's worth it. It has some issues that are concerning, such as water in the gear oil, lots of missing parts, etc. I downloaded the '75 service manual and it has a simple diagram of the ignition system. Is the battery necessary for spark with these bikes?
Thanks again, and have a good New Years!

One wire from points to coil.  Job sorted.  You need the black/ white wire coming from the mag connected to the coil.

Great, thanks! I will try that.

As Tinkicker say, one wire from mag to coil.
Might be straight black from the mag 'without looking' & 'think' black/white would be when switch is involved & linked back to the black to ground it as a kill switch.
Happy to be Kicked by Tinkicker if i'm wrong lol.
If you go 'that way' to get it running just be sure to have a way of stopping it if necessary if for instance the throttle sticks open--eg pull wire off, &/or have something solid to put across the carb mouth if air filter hose is off.
Talking unlikely extremes but S@#t happens.

That's a good point, I'll make sure to do that. The carb will definitely need some help before I can test anything anyways. The oiler system is very incomplete also, so I will have to run premix for the time being. From what I understand, these bikes generally like 20:1 or 32:1, right? I want to restore the auto oiler but it is missing a lot of  components so I don't know if that will ever happen.

As well as looking out for a replacement complete oil pump, it's also worth looking out for a right hand side crankcase cover with an oil pump still attached - these listings often offer good value and you can sell on the cover itself to recoup some of the cost.