Hi all,

My dt250e in my ownership has never had the airfilter guide.  I am currently just using chicken wire to keep the filter from collapsing.  I have  not had much luck finding one for sale.  Any one know where i can source one for a reasonable price? If not maybe some pictures of the oem one with dimensions?

If you are running an original filter (see link below), you could measure the internal dimensions of the filter and add a couple of mm to these, just so the filter stretches over it.

ELEMENT, AIR CLEANER for Yamaha - order at CMSNL

If the airbox is like that on other Yamahas I've seen, there should be a slightly rounded triangle protrusion, which is used to locate the filter cage. You might even be able to measure the internal width of the airbox.

Mind you, I'm not familiar with that model, so the above could be bollox!

Have you tried buying a filter from Yamaha?  Sometimes they come with a cage on the later monoshock models.  

I bought a NOS filter but it was through ebay and did not come with the cage, good to know that they may come with it from yamaha.  The air filter box does have the triangle protrusions so i could use that as a reference for fabricating something.

Yamaha one might not have a cage either.  Partzilla has them on sale for about $19.  

(Always check Yamaha for parts first...  many ebay sellers list "NOS" parts for huge markups over what you can buy it for new today directly from Yamaha. A lot of people must never check with Yamaha because I see a lot of "NOS" parts on ebay that Yamaha still sells new for less.)

I don't have mine anymore or I'd measure it for you.  Another option was K&N made a filter that you might find and it doesn't need a cage.
 

It looks like Bike Boneyard has a 77 DT250 and a 78 DT400 they are parting out.  You might try contacting them and seeing if either has the air filter cage still.

bikeboneyard.com/

It still is possible Yamaha one does come with cage and the "NOS" ones are older ones that Yamaha wholesaled without cages?  I bought mine a few years ago and can't remember if it had the cage or not.  

Another option is the UNI filter which should have a cage.

Here is a UNI that looks like it has the cage.   ebay UNI NU-2232 filter

Hi, Mat c here from Australia. I’m currently restoring three dt250A’s. I had your same problem about filter cages. I have one and needed two more so I made one with aluminium gutter guard with u shaped rubber strip on both ends to hold it together. Overall dimensions of 122mm x85 mm x63 mm. I don’t know whether I can provide photos yet because of insufficient posts,  but I’ll try. By the way it’s really easy and works perfectly.
 

A DT360A I purchased was missing the air filter and cage so I purchased a Unifilter (as Mark mentioned) and removed the foam from the cage and used a new OEM foam from Yamaha. The foam that came on the Unifilter assembly was so restrictive the engine would misfire in the higher RPM range with stock jetting. It ran fine with the OEM foam/Unifilter frame combo.