77 yz almsost same thing 

Well, the plastic welding repair has started to seep fuel, and as feared, the seam on the tank has separated another couple of inches. I have tried closing it up with a soldering iron, even adding "donor plastic", and it still leaks. I did find a YZ100 tank that does fit the frame. It looked to be in really good condition, but cracked just cruising the neighborhood. Frustrating, as the bike is in excellent condition, just no replacement tanks to be had. If anyone should run across a 125 tank, please let me know.

There's an IT125 tank on ebay right now...  looks weathered. 

You might also try calling or email Speed and Sport Yamaha in Bloomsburg PA.  They have a ton of NOS parts...  stuff nobody else does.  Cindy is great to work with. 

Don't bother e-mailing Speed and Sport, I've e-mailed them a couple of times with no answer, I'd give them a call. I will be calling them when I'm ready to start on my DT175, they have some parts I can't seem to find anywhere.

Hey Mark T, when was the last time you went to Speed and Sports website? I just wend nosing around and it's changed, can't find any DT parts. I clicked on an old link I had saved and got the dreaded 404 error. I went looking to see what parts they had for my DT175, all they had was parts for a TY175 and not a lot of those... Just thought I'd pass that on.

A few months ago they said they were taking the site down to update it.  It still isn't back up which is why I suggested calling or emailing.

Thanks Mark!

start over on all the repairs, cut a v groove, fill  with water, in a big tub of water, and go a little bit too long with the welder and eventually even your tank will stop crying so much.

Hello,
l’m in the same boat looking for a couple of IT 125 gas tanks. I contacted Gilimoto of Brazil about building some tanks and they are interested in building one but need about 40 tanks to start the build. I’ve got interest in about 33 tanks on some IT Facebook groups. 
If you haven’t heard of them look them up. They just recently built a 81/81 IT 250/465 tank and have built some for kdx, pe ang many more. If you would be interested please let me know. Also let anyone else that may need one know. 
The tanks will be $225 US plus shipping. 
I will message you my phone number if you want to talk.  
Thanks

Blue Frog,
I would be interested in a tank if Gilimoto decides to make some. Let me know if you need any specific info. Thanks for the response to my post.