I am cleaning up a 1970 DT1CM, and there are no vent hoses or barbs on the carb.  Is that correct?  Seems like dirt can get in to the carb easily.

The parts diagram shows a hose as part number 37:
 

Top of carb chamber showing where vent holes come from:
 

Where the vent hose(s) should go:
 
 

Can I press in little brass hose barbs?

Should I just run it and not worry?

Thanks, Jay
 

One is vent and the other overflow?

I would check first that both passages are clear and then press in replacement barbs, if you can find any. I was lucky enough to get some in a job lot of carb parts that I bought a while ago.

They are vents.  Both are clear now but one was packed with dirt at the outside opening.

I ended up making vent barbs with brass tubing, wire and solder.

 

They just press in the vent holes. They can be pulled out if someone far in the future wants the carb to be original.

 

Nice work!

Should have been barbs in the carb originally?  I've seen them pull out with vent hose and get lost. 

MarkT wrote " Should have been barbs in the carb originally?"

That is what I thought!  One is shown in the parts diagram.  When I went scrapping around on old carbs I have laying around, I found the small barbs are all 3mm diameter.  The vent holes on this carb are 2mm.  I didn't want to drill my carb out to 3mm, and thought I would tear up the barbs trying to get them out of the old carbs.  I searched pictures on the web and didn't see any DT1MXs with vent hoses.  Most pictures of DT1s do not have the vent barbs, but some do.

Often on "promo" photos they leave stuff like that off to get a cleaner picture...  like most car and truck brochure photos have deleted the radio antenna for many years. 

It's also possible they didn't have the hoses on the MX...  one of the old racers might remember.