Do you mean that you can still get them OEM? I have not found that anywhere and no I haven't replaced that O ring but it does come in the kit that I won't be buying. I'll look for what you are talking about and Merry Christmas!

Nevermind, think I found the OEM parts where you just buy the parts that you need not as a set. Thank you for your guidance as I try to figure all this stuff out. The site I found it on is BikeBandit.

Buy the oring from Yamaha... RMATV-MC has great service. yamaha-enduros.com/index.php/component/banners/click/5

Jets are standard Mikuni so can save some $$ by buying from a Mikuni distributor like Niche Cycle... old jets have numbers on them so you get the right size... good idea to check this as Yamaha parts list often has several "alternate" jets listed so can get confusing if you don't know the size.

Did you check the choke well in the float bowl, it feeds thru a little hole in the bowl .

Have you checked the throttle cable barrel adjustment on top of the carb? I was having a terrible time getting CS3-200 to run right after a carb cleaning and discovered that while unscrewing the cap to pull the slide out, I had completely adjusted the cable to where I was starting it with the slide wide open. The barrel adjuster is under a rubber sleeve so I didn’t see it. Mine would start though, but wouldn’t idle (fairly obviously to any mechanic better than me). I’m slowly learning with each new mistake.

Looks a little like Brian May...
Hey...where did Nodward go?

James May?

That O ring as mark stated can cause a lot more trouble then you would think its something i would replace. Looks like everything is correct BUT do the floats slide up and down on the shafts freely? if their snagging that's no good also if they have a hole in them that's no good either. Another thing is check the reeds. I have a PW50 that i bought for dirt cheap and upon rebuilding i couldn't figure out why it wouldn't fire, turns out a piece of debris was holding one of the reed "flaps" open and i was loosing too much compression. Lastly is spark just because you have spark doesn't mean its good spark. Need to shoot some gas into the spark plug hole, not much but just enough to make it pop.

Brian May...guitarist for Queen who is also an astrophysicist...
But whoever posted the photo has taken it down.

Noddy is still around and doing bits and bobs on UK tv and radio. He refuses categorically, though, to re-join Slade.