I've rebuilt carb on my 175F and struggled to get the float height correct.  Manual says 21mm and it appears that that measurement should be (judging from the poor photo in the manual) from the lower lip of the carb body.  All online stuff I have found suggests that the gasket seat face (a few of mm recessed from the lip) is , I have finally got it to stop leaking whilst it's in my hand.  But when I move it about, there's the occasional  little spill coming from the hose.  Now the overflow pipe is on the right side of the carb, so on the side stand, that would be a high point and as such, there would be no   It seems logical that it might be, and not something I'd have noticed in normal   it's just that I'm looking at it now.I've rebuilt carb on my 175F and struggled to get the float height correct.  Manual says 21mm and it appears that that measurement should be (judging from the poor photo in the manual) from the lower lip of the carb body.  All online stuff I have found suggests that the gasket seat face (a few of mm recessed from the lip) is , I have finally got it to stop leaking whilst it's in my hand.  But when I move it about, there's the occasional  little spill coming from the hose.  Now the overflow pipe is on the right side of the carb, so on the side stand, that would be a high point and as such, there would be no   It seems logical that it might be, and not something I'd have noticed in normal   it's just that I'm looking at it now.  I've rebuilt carb on my 175F and struggled to get the float height correct.  Manual says 21mm and it appears that that measurement should be (judging from the poor photo in the manual) from the lower lip of the carb body.  All online stuff I have found suggests that the gasket seat face (a few of mm recessed from the lip) is , I have finally got it to stop leaking whilst it's in my hand.  But when I move it about, there's the occasional  little spill coming from the hose.  Now the overflow pipe is on the right side of the carb, so on the side stand, that would be a high point and as such, there would be no   It seems logical that it might be, and not something I'd have noticed in normal   it's just that I'm looking at it now.I've rebuilt carb on my 175F and struggled to get the float height correct.  Manual says 21mm and it appears that that measurement should be (judging from the poor photo in the manual) from the lower lip of the carb body.  All online stuff I have found suggests that the gasket seat face (a few of mm recessed from the lip) is , I have finally got it to stop leaking whilst it's in my hand.  But when I move it about, there's the occasional  little spill coming from the hose.  Now the overflow pipe is on the right side of the carb, so on the side stand, that would be a high point and as such, there would be no   It seems logical that it might be, and not something I'd have noticed in normal   it's just that I'm looking at it now. 

The measurement is taken from the gasket sealing surface , not the lip .
If the gasket is in place , and you don't want to remove it , the usual thickness is 1mm ,
so deduct 1mm from the specified measurement .
 

Welcome from NZ. looks like you're new. I'm guessing you tried to load photos which doesn't work unfortunately & looks like it duplicated your post each time. Try linking pics through "imgur" or similar. But anyway, is there possibly something else causing leakage. There's a resonable give & take with float height before it'd spill out the bowl breather. Is the side stand leaning over extremely. & something i'd never ever thought of till now but do US models have the side stand on the right where ours is on the left down here. I guess that's a stupid question now i've asked. I've read of the breather tube cracking from others on the forum, not neccesarily DT175's but that's be unlikely. I'm not sure on your carb but i've fitted a clear hose to the type that has a drain screrw you loosen to let it drain out the tube fitting under the bowl. Screw is tappered so just blocks it off sideways. Then with a clear hose curled up the side it's clear to see the level. I'm probably thinking of a 4 stroke carb on something that was @##$ing me off.

  what I thought, but not what the manual shows me.

Hi, , new and struggling with this platform.

Pic was not really relevant.  Just a pic of the carb.  
Stands?  Pretty well universal as far as I know.  I've toured EU extensively and never seen a stand except on the left (with the exception of Trials   never understood why they are on the right).
Carb now has clear tubes, but no shut off - overflow only.  
I remember in my teens knowing changing float height was a solution, but now 50 years later I read stuff online saying it will affect mixture.  Anyway, just spoke to a mate who is an ex-race mechanic and he tells me I am right, just need to add another millimitre or so and that mixture will only be affected if you're doing it to tune.  I just need it to shut off.  So I reckon I've got it nailed.  I jus put the original gasket back in too as the new one is about 0,5mm thicker which won't help.
Thanks

Look forward to the result.
Hope its not a dodgy float valve or a leaking copper float that's got fuel inside weighing it down.
Unless it's the black plastic type floats that rise on seperate pins. They don't go bad.

My dt175 had an intermittent overflow due to a crack in the copper (?) overflow tube. Was very difficult to spot as super hairline.

After hours of fiddling, I decided to fill the bowl with fuel away from the carb.  A slow leak was still there.  Blocking the entrance to the capillary tube and blowing into the overflow hose, bubbles everywhere!  The tube is cracked!
Thanks for all the attempts at advice.  I now need to get a new one.

I got some slightly oversized tube to sleeve it and flooded the “gap” between the two
tubes with solder. Didn’t work and ended up with a replacement bowl!