I ordered 2 needle jet o-rings last week and and the ones I received were much smaller than my older one.  They are smaller in diameter and not as thick, so when I put the socket on it it slipped out of the socket.  It feels like they don't even seal.  The part number I ordered was 214-14147-00-00. Is this the correct part number?  Or does someone know what size the o-rings should be?

I believe that is the correct number, although I'm unsure what you mean by "socket".

it does appear to be the correct number however the o-ring is much too small in both diameter and thickness. I had ordered 2 and they both are visually much smaller than the original.

Daft question, sorry, but I assume that they are original Yamaha parts in Yamaha packaging, and not repros?

here you can see the difference and my original is a little ragged.

imgur.com/a/FAnrwv8

here is one still in the package.

imgur.com/a/lwoWJ8d

Can you post a picture of the o-ring installed on the needle jet?

Maybe someone had adapted some Oring to do the job. Original is quite thick by memory. Albeit small!!. Bottom line is does the bowl feel like it's compressing it somewhat when fitting the bowl. I'll loose my place if I look back but think you said socket fits over it do I assume you mean socket wouldn't go over the one you removed--because it's too big or swollen. I'd think the socket to undo the jet setter probably would go over the 214 Oring or might just touch it but not get in the way of the socket. Quite a deep groove where it fits in.

One more thought. Do you have the thick brass washer the jet setter goes through as it sits the jet setter quite a bit lower & with a large lead in like the bowl has it could make the difference between compressing--or not, with the Oring. Bit of guessing on my part without looking at one of mine.

For Info Only: I thought the same when I put a new oring in my DT1. When sliding in to bowl, no resistance ( of course I grease mine). So, I went to ACE Hardware and bought a few that were slightly bigger. In my particular case, all that happened was it ran the same and was harder to put on. I guess those factory orings are the correct size.

Your carb, diff than mine of course. Looking forward to the outcome and findings.