Hi everyone!
I'm going to be documenting the restoration of my 1976 Yamaha DT250 Enduro in this thread. It's going to be a long road, and it will be fun to share the progress with you all here! As I go along I will try and keep this updated with my project.
First off I'd like to thank Gr8uncleal, MarkT, Tinkicker, DEET, and RT325 for their help in a previous thread. It would've been a lot harder to figure this out without your help!

Here's a few photos of the bike, apologies for the poor quality, the sun was going down:
Left side
Right side
Engine, right side
Engine, left side
Tach cable
Speedometer
Tachometer
Ignition Cylinder
Gas Tank
Inside Gas Tank
Gas Cap

The story behind this bike is this...
I had a 1984 Honda XR500 that I got for free from Craigslist. The bike was kind of a mess, it needed a lot of parts that weren't really available and it needed a lot of welding. But it did run and ride! Around the same time, my friend picked up this DT250 off of Craigslist for pretty cheap. He couldn't get it running, so I suggested a trade. I had never seen the DT250 before I offered the trade, and if I had, it might have been a different story... Anyways, one trailer ride later and I had my very own 1976 Yamaha enduro.
It was one of those bikes that the longer you looked at it, the worse it got.

Let's start with the good:
-It has a clear title in my name
-It (kind of) runs
-The frame is solid
-It has the original Mikuni carb

The bad:
-Everything else

It is missing the wiring harness, the seat, seat pan, oil tank, air box, the front brake cable, the speedometer cable, the tachometer cable, and probably a few other things that I don't remember right now. The gas tank is rusty and filled with huge sheets of peeling paint. The cylinder is pretty scored. When I got the bike, the cylinder was filled with rusty sludge water mixed with oil and the transmission was also filled with water. The crank bearings have a pretty good rumble. It didn't have any spark, and the carburetor was filthy.
Soon after I acquired the bike, I moved across the state and the bike sat in the shed for 9 months, ignored. I finally was able to haul it out to work on it again last month, and with a lot of research and time I was able to restore spark. Turns out the cheap Chinese ignition coil was to blame, who would've thought? After I restored the spark, I bottle-fed the carburetor an oily two-stroke mix, and to my surprise it actually fired up and ran. It not only ran, it revved and idled too! I have no idea how many years that bike sat before I got it, but I think it would be in terms of decades. The tach cable was missing, and the hole that it left allowed water to sit in the engine case for untold years. It sat outside on the West Coast of Washington, so lots of rain and moisture was a given.

That's basically where I'm at right now. It "runs", but it needs a million parts and a lot of time before it's roadworthy again. I think my priority at this point is to get the fuel system and oiler system functional and try to get it to move under its own power. I have already ordered a handful of parts, hopefully they'll start coming in soon.

I would love to hear your opinions!
-What should I do with the gas tank? I have heard many people swear by Evapo-rust, but I wonder how well it would work with the loose paint that is in the gas tank. I don't currently have the money to get it professionally cleaned and painted, so it will be a budget DIY job. I think the paint removal will be the hardest part.
-Has anyone had any luck making a seatpan for one of these bikes? I've seen some pans on ebay and such but they're all $150 or more. Wondering if there's a cheaper way to make one from plywood or steel sheet or something similar. I have a seatpan and seat foam, but they are not for this bike. They're for another Yamaha, looks like maybe a DT1? In any case they won't work for my bike. Maybe someone on here could use them?

Whew! That was a lot to type. Thanks for reading! I hope to update you guys again soon, maybe even with better pictures if I can get my phone working.
-Daniel
AKA "Superslug360"
 

You definitely have your work cut out for you, just a heads up, that speedometer, tachometer, key switch and kickstart lever are not correct for your bike, that’s not to say they can’t be made to work, they look like they are from an older Yamaha model.
If you have any questions I have had several 75-76 DT250-400’s and currently have a 1976 DT250 I am the second owner and have owned it since 1976

"just a heads up, that speedometer, tachometer, key switch and kickstart lever are not correct for your bike"

Agreed.

Ignition switch will be from a late CT1, CT2/3 or late DT1/RT1 or DT2/RT2/DT3/RT3 - closer inspection of the wire arrangements in the blocks will be needed to confirm. Quite a valuable item, so sell on to recoup some of your costs.

Tacho is from AT2/3 and CT2/3. Speedo is from any of the 1972/3 models (but double check the ATs). Again, some value attaching to these.

Your switchgear might be 'wrong' as well.

As the block connectors on the ignition switch haven't been messed with, maybe your main loom has?

Oh my goodness, this is a super project. I was going to say, amazing because you have the key, but just learned that it's not really the right one, oh well. Good job on getting it running. Like you say yourself if you take it slow and easy and put the word out on the street perhaps parts will gravitate towards you and you can keep moving forward. Like to see how you handle the tank. I am sure you could find all sorts of things to work as a seat.

Thanks for the replies! I have been busy over the past few days sourcing parts and trying to figure out what I still need. I got a good deal on ebay for an oil tank, and my throttle/oil pump cable came in from HVC Cycle yesterday. I'm planning on using evapo-rust to try and clean out the gas tank, we'll see how that goes.

Lizeec, you are definitely right about the mismatched parts. I'm not knowledgeable enough about these bikes to know where they all came from, but there are a lot of things that don't look quite right on this one. Thanks for the offer for info! I will take you up on that for sure when I get a bit further along assembling this bike.

Gr8uncleal, I believe you are right about the ignition switches. I compared them to my wiring diagram and they look nothing alike. It does have an original Yamaha key in it, so that's pretty nice. I think the lock itself is pretty worn though. It turns, but it's sloppy. As for the main loom, it's totally gone. I plan on making my own, but for now I will make do with minimal wiring.

Reed valve richards, I'm leaning towards finding a nice piece of plywood and cushion foam to DIY my own seat. I tried finding parts locally but no luck. I have had luck in the past making a seat, I have a cool older Sears & Roebuck minibike from the early 70's that I made my own seat for. That bike is a whole story in and of itself.

If anyone has use for some of the older parts I have for this bike, I would love to get rid of some of them. I think I will probably hang on to the tach/speedo for now since I can probably make them work. I have a few more parts that aren't pictured, I can get a few pictures if anyone wants.

Does anyone know where to get a cable guide for the top of the carburetor? I realized after I got the throttle cable that mine is broken. I think the part number is 363-14155-00-00. I've done a bit of looking around on the internet but it seems like they are pretty much sold out everywhere. I have the part that goes into the carburetor and has the circlip on it, but the angled neck is broken off. If I can't find one, I will probably just try to jury-rig up something to work for now. I have a 3d printer and it has been wonderful for temporary and mock-up parts.

Thanks again for reading all this! I will update more as I get more stuff sorted out.

If you can post a picture of the carb elbow, someone might be able to help. 

Quick little update today.

Here is what's left of my throttle cable elbow:
imgur.com/a/XJuxE1s

And here is what I think it should look like:
www.cmsnl.com/products/tubewire-guide_3631415500/

I still haven't made any headway on finding a new one, seems like they're made of unobtainium.

Right now, the gas tank is soaking in Evapo-Rust with a bunch of roofing nails inside to knock loose the crud. It's a lot worse than I thought, it seems like someone put some sort of gas tank sealant in it awhile ago and it's all coming loose. I have big chunks of silver paint/sealant coming out. On the plus side, it doesn't appear to leak. Pictures coming soon on the gas tank.

I'm making slow progress on the oiler system, I think I have all of the parts to get it working again, just need to get the throttle linkage setup before I can really test it.

That's all for now, I'm hoping to get the tank cleaned out so that it's usable next. Thanks for the responses again, it's been fun to actually keep track of a project for once!

Might be something on here that will do. If the link works. I'll try & see if it comes up.
www.ebay.com/p/23035386960

The person before me put a straight cable guide on my 360...right in to the exhaust.
Not sure, but I think both your bike and mine use something like a 40 or 45 degree??
Once I mount my carb, I'll know more about mine, but till then, a few options below:


jetsrus.com/carburetor/carb_mikuni_VM18_...oded_view_parts.html

mikunioz.com/shop/70-degree-throttle-cab...arbs/?v=13b249c5dfa9

Thanks for the options! I think I will first try to drill out the old one and try and fabricate a new piece. I don't really have anything to lose messing with that one. I would like to keep the new cable from resting on the hot exhaust! I think I could probably get a piece of steel or brass tube and a thread cutting die, and some sort of epoxy. We'll see how it ends up!