Gday all. Just joined recently. As Im about to start a new DT250 rebuild.
From Queensland Australia. Ive done a couple of DT rebuilds before. But that was over a decade ago. And now finding it very difficult to source parts and info. So here I
Cheers
Craig

Greetings from Tennessee USA 

 from near Salisbury, UK.

Sites like CMSNL and Partzilla often show which other models used a certain part.  Whilst they are very heavily US biased in terms of models covered, there will still be good info there.

What Alan suggested is extremely valuable!  One thing to keep in mind is that what CMSL/Partzilla/etc actually shows is what other "parts lists" that part appears on.  

Yamaha kind of made a mess with their "shared" parts lists when they were digitized from books and fiche.  Sometimes you need to be careful and it can be difficult to ID the part you need.  

The 250, especially the earlier models, shared lists with the 360/400 so sometimes extra attention needs to be paid to identify a part like a "piston" as obviously a 250 piston is smaller than a 360/400 piston and often the parts list doesn't make it clear which is which.
 

Good points, Mark.

Also with CMSNL, whilst they may not have parts lists for all markets, they may have parts in stock for them. Instead of searching by model, type in the part number you're after and, if you're really lucky, they may have it in stock.

I actually find it AMAZING how many parts are available still.

Here in the US in the 1990's it was really hard to find parts.  Dealer or a wrecker was the only source and the dealer near me did not have any interest in the older bikes...  the "mom and pop" Yamaha dealers were mostly gone and the new "big company" that had the Yamaha franchise didn't even have the old parts books (or they didn't want to be bothered).

A neighboring town had a motorcycle wrecker and I spent countless hours there digging.  They had a few more or less complete bikes outside but most parts were in huge totes inside a warehouse marked with something like "yamaha carbs" or "yamaha gauges" that you'd pick through to find something you could use.

Actually much easier today with the Internet.

Agreed.

For a while in the late 1980s here in the UK, a company called Rafferty Newman bought up loads of surplus old Yamaha stock from dealers and turned it over nice and cheap. My interest back then was solely RDs, and I recall picking up a couple of brand new petrol tanks for next to nothing!

I think that CMSNL have been, and are still doing, a similar exercise now, although the prices are through the roof, unfortunately!