Wayne I have not seen a needle and seat in the flesh yet, I have only seen pictures. Have a look at mikunioz.com, needle and seat assemblies and see what you think when you get a chance. Also a good online source for jets although they only appear to have them in some sizes.
Allen, there are no numbers on either the needle or the seat. I know that you have seen it, but here's a photograph so perhaps someone with more experience may recognise commonality with another part. The RE5 part numbers are 13370-37010 M and 13370-37011 for the A. I doubt that there's any practical difference.
I have also had a look at the mikunioz site and of the 20 pictured, none look the same. The RE5 seat has a distinctive Tapered brass section below the main threads. No other assembly has this although they do have similar dimensions other than that. Perhaps at least one of those would fit anyway ?
Wayne thanks for the info and photo. The needle and seat in your photo is different to what other photos I have seen, for instance there is one on eBay out of the states which is similar without the taper on the end of the seat, which is what I have been using as a referance and is simular to what I have seen on Mikunioz I will have to wait and see when I dismantle my carb.
It's been a while since I had the carb apart but from the diagram, I think you're right. I always run a paper in line fuel filter between tank and carb anyway and recommend doing the same. You probably don't need that filter (the petcock has fine gauze filters as well.
Sydney, Australia. The new leaner, trimmer shed: RE5M, RE5A, GSX1100EX, GL1800/Champion sidecar