Also it looks like my rt3 bowl is deeper than my dt3 bowl. Dt3 is stamped 311 and rt3 is 308

Ahh, the plot thickens. You'll be the expert after its sorted & know all the tricks, bowl swapping carb to carb & traps to know of.
If ya run out of options--just do the jet straight into the needle jet--i'd better stop saying that & p---ing people off.
I feel good news coming in the next post.

The "chuck" side of a 17/64" drill bit drops into the well on my DT3 bowl.  The next size up in my Harbor Freight drill assortment is a 9/32" and it will not fit.  (Be sure there are no burrs on the bit from a chuck slipping...  my bits are a new set I bought on sale a while back and haven't screwed them up.... yet!)

On some Mikuni's you can thread the hex main jet into the needle jet... not on this one.

The 164 series needle jet and jet setter are a different thread (metric) from the (Amal-type) hex main jet (standard).

You could use a "small round" Mikuni main jet in the DT3 164 needle jet as it has the same metric thread... but the numbering and calibration is not the same. (The round jet numbers are smaller for the same flow)

It's not exact but online charts say a 165 hex main would be about the same as a 117.5 small round main that would fit your 164 needle jet.

The reason I'm mentioning this is because RT325's idea is a good one... before you going buying tons of parts and maybe getting nowhere you could try a 117.5 (or slightly larger to be safe) small round main jet in place of the jet setter (remove the hex main from the carb completely!). This bypasses the whole o-ring arrangement and for like $5 you'd know if that was the issue. (Local motorcycle shop should stock them, small round was used in a lot of newer Mikuni designs)

Here's the jet I'm talking about that has the same thread as your jet setter. www.nichecycle.com/ncs/categories/carbur...n-jet-by-mikuni.html

Sounds good, thanks for that info. I’m out of town for work for the next few days so I won’t be able to measure or get started on that till the weekend. Thanks RT and MarkT you guys are a tremendous help. For some reason mark your link doesn’t work but I will look it up and find what you are talking about. Hopefully this can solve my issue!

Link works for me?  Niche Cycle.  Anyway, small Mikuni round jet is a N102.221 (aka N102/221) series. 

Here's another (more expensive) supplier:  jetsrus.com/a_jets_by_carburetor_type/je...main_Small_round.htm

Here's one on Amazon (too expensive) but lists a lot of machines that use the jet...  a motorcycle/quad shop should have them.  www.amazon.com/Mikuni-122-5-Yamaha-KODIA...0-2001/dp/B079XYRJM7

 

That's very useful info on what jets fit what & calibration differences.
Things i often wondered but never researched.
I must go read up on stuff. Thanks MarkT.
In fact i probably would have gone for the same size hole. So what changes.
Or are the holes the same but numbered different.
Or do they flow faster smaller because its shorter throught the middle compared to a long jet.
I'm just lazy & not researched yet but i'm sure MarkT knows.

Thanks for the links and the info. Found a shop in town that had some on hand so I should get to testing it out this weekend! Hoping for good news. 

So I put in the 120 small round jet, and it ran very similar as before. I decided to start with the more rich one just in case but I’ll give the 117.5 a shot next although my hopes are low. I’m starting to be convinced of low compression or I messed up the condenser relocate although the issue is the same as before I did that. I guess it could be as RT said that since it’s been rich for so long it needs to run a while to burn out. I only ran it for 5 min before shutting it down. 

Are you sure the timing is correct?