I can tell you - that is a very nice factory (OEM) accessory desert tank available in the 75-76 Yamaha Accessory catalogues. We have copies in the download section if you want to see the other cool stuff they had available. The nice thing is it uses a stock petcock, giving you a reserve function.

I have a couple of these used on the Trans America Trail Ride bike.

Cannot seem to find it in the download section,what heading are those accessories under?

In the dealer brochures!

yamaha-enduros.com/index.php/workshop/de...y-catalogue-for-1976

yamaha-enduros.com/index.php/workshop/de...-accessory-catalogue

The 1974 DT250 pipe is essentially the same pipe as the 1975 -76 DT400 MarkC just posted on. The stock pipe is woefully
weak on performance IMHO...so the Sleeper Mod helps the pipe work a lot better.

In regards to the MX250/360 pipes...they are pretty decent from the factory from what I can tell?
Although I haven't played with those pipes firsthand...
I remember in my youth riding a brand new DT2MX on several occasions .....
and from what I recall the bike made some real good power.

The MX360 doesn't need a sleeper pipe . . .

Dave - I have an interesting possibly factory expansion chamber for a DT400B/C which might be interesting for you to see. I could toss it in my truck for Cal Dreamin.

What is interesting is it follows the factory route, and appears to be designed to connect to a factory silencer tip. I plan on using it on one of my upcoming builds, but it is NOS at the moment.

Let me know if you're interested.

I would like to know how well it actually worked ? I wonder if it a low-end, midrange or top end pipe ?

Most enduro guys like low end mid range pipes...as that's the most useful for us "old guys"

I have found most expansion chambers...of that are were top end pipes. They produced a lot of upper end horsepower
for racing. Not what you want out on the trail.....

Well - until I build it I won't know!

As I said, it is NOS so I can't tell you what performance specs it may have. It has no identifying marks, and was marketed as a factory part number. It does have mounts for the stock heat guard, and is nice quality, so it could be a factory part.

If I remember I will try to toss it in the back of the truck and you can take a good look at it.

Have you considered installing on one of your DT400's for a test ?

Of course I've considered it. Just haven't had time with the other projects ahead of it. I do have the TAT bike which is running reasonably well which I could test it on. Let me see if I can get that organized . . .