So I am doing a bottom end rebuild on my 250D and I have separated the cases enough that the crank is no longer in the right side bearing and the dowel locating pins are not in the case. The cases have some play and all the shafts in the picture move freely relative to the rightside case. However it is caught up on something and after a bout an inch and a half it hangs up on something preventing me from moving it. Do I have to remove the circlip from the shaft in the center of the photo to fully separate them? 

EDIT: Well apparently I cant upload photos I keep getting a "Could Not Move File Into" error 

Edit 2: imgur.com/SZbuhxP 


 

You have to upload pics to a 3rd party site like Imgur and link them here. 

Can't think of anything & looks like you've got it covered & even removed the retainer on the gearbox mainshaft although uneccessary but doesn't matter--so can't think of anything unless the spacer throught the top rear mount is hung up on the Orings centralising it.
Na that'd be unlikely. Providing the two shafts & selector drum all move through together--i'm lost. Take the plunger & spring out from other side underneath but won't be stopping it parting, just gets in the way if the drum moves away then cant go back because it'll jump up behind the cam plate [that's not helping sorry].
Good motor those but i never had mine apart, just thrashed it to work from cold .
Star pin retainer on the drum not catching on the way through the needle bearing--unlikely.
Circlip on the gearbox mainshaft bearing doesn't need removing.
Key on the crank still there & hanging it up from clearing the bearing.
No Oring on the mainshaft resisting in the bearing.
Ok you say the crank has cleared the bearing. I'm lost, should just about shake apart from where you're at.
But keep on being careful.
Umm one more--one or two screws still in place by a few threads on the other side.
www.partzilla.com/catalog/yamaha/motorcycle/1977/dt250d

My wild guess is this:



If I remember correctly, the later 175's require the the "ratchet" plate and pins removed from the drum to remove the drum from the case.  Pay attention to the orientation in case it matters how it's reassembled...  just a guess though.  Not sure if 250 is the same. 

Yes do hope ya right Mark!! but only the pins come out so my thoughts are not necessary. Did wonder if that bit on the pin retainer that curls over one pin is catching the needle rollers but i've convinced myself they'd design it 'not to happen'. Frustration to get 'that far' & no further. Recheck no case screws on other side hanging in there by a turn or two. Does t come up solid with a clunk or sort of rubbery at its limit.
www.partzilla.com/catalog/yamaha/motorcy...977/dt250d/shifter-1
Selector shafts need a bump. I see one heading out & other sticking out but i guess that one has the claw arm swinging on it hence is long.

 I dont believe this is it because that drum has so much play in that hole but I'll give it a shot later and update here after I get a chance to spend some time in the garage. 

There is a factory service manual in the Tech Library it might show you how to split the cases

If drum is loose in bearing, probably not it.  Can't tell that in picture and I'm pretty sure the 175 plate needs to be removed.

RT325 mentioned the spacer in the upper engine mount.  Usually the dowels are the tough part it they got corroded.  But I did have a 175 with that spacer stuck.  It was pretty obvious corrosion in the hole though.

I removed the plate and it definitely is not needed to separate the cases. Does the pin thats just above the shift drum that you drew the line through come out of the case? If it is supposed to I think that may be what is holding it together. 

we can't see your bike and that pic was from a manual.  I'm guessing that "pin" is the shift fork shaft #16 here:

www.partzilla.com/catalog/yamaha/motorcy...977/dt250d/shifter-1

If it is, it should come out of the case.