I'm down to the finishing touches on reviving a DT250A. How are the vent hoses routed and where do they terminate? Two crankcase hoses (cover and case itself), carburetor (2?), oil tank, and battery vent hoses need to be addressed.

The 1974 DT250/DT360 Factory Service Manual (available in Tech Library here) has fairly comprehensive routing diagrams near the back.

The 1975 manual has a little more detail and is worth a look if I remember correctly.  

Note: The bike should have had a decal under the seat showing the (critical) correct routing of the battery vent hose.  Reproductions are available pretty cheap last time I looked or you can find photos of the decal online fairly easily.  (Hint: searching the Internet for the part number of the decal usually finds one pretty quick. 438-28179-00)

Sometimes looking thru the owners manual and service manual you will see pictures of the carb area and vent tubes. I see a good picture of the carburetor in the owners manual on that bike that shows your carb vent tubes and both case vents.

I have a friend that has a DT250A with just over 100 original miles on it. Still brand new but he's to far away for me to go look at it to check the hoses. I've been trying to buy it now for 5 years. Maybe someday!

"Sometimes looking thru the owners manual and service manual you will see pictures of the carb area and vent tubes. I see a good picture of the carburetor in the owners manual on that bike that shows your carb vent tubes and both case vents."

Generally sound advice. HOWEVER! Sometimes Yamaha use generic, non model specific photos to illustrate a part. For example, I think in the RT3 owners manual there is a photo indicating the clutch lever, with no decompression lever present on the perch. However, they use a photo of an actual RT3 lever and perch to show the location of the decompression lever!   

Correct, that's why i used the word "sometimes". Usually you can tell if the picture is the actually bike and model needed as is the picture of the carburetor i mentioned in the owners manual.

 

Yes, the decal is still there. That happens to be the only one that the routing was evident to me. Carb and crank case hose routings are still in question, however. Thanks for the reply.

Somebody correct me if I'm wrong, but it appears that the carb and one of the crank vent hoses are tucked behind the left side covers pointing downward. The other crank vent hose appears to basically follow the same routing as the battery vent facing upward. Maybe I'm being a little anal about this, but the rest of the project has gone very well and I hate to not finish the job as correctly as possible.