Good replies, thanks.
Racingplanetusa has all the Arreche stuff you need, but it takes forever to get anything from those guys. Thing is, I don't know what to buy for tuning. Until I figure that out, will wait to buy. The more I look, the more I learn, but not very efficient, I spend hours looking and pick up a little here and there.
Pace, I read your thread, good job and initiative, you are fearless dude. I want to keep oem parts as is, so I can easily go back to oem carb setup. I've been through the Treatland carburetor section a couple of times, all 1000 plus items. They have a lot of stuff, but best I can tell it's mostly for moped. These carbs come configured all sorts of ways, like the screw adjustment and idle adjustment can be on the other side of the carb, different top caps, electric or manual choke, different connections to manifold (bolt on, slip on), ...
I did some calculations for area of the different size carbs. 16mm is approx 201mm squared, 17.5mm is approx 240mm squared, and 19mm is approx 283mm squared. That means 17.5mm has approx 20% more area for fuel/ air mixture to flow through than oem carb, and 19mm has approx 41% more area. It doesn't take much diameter increase to effect a big area increase.
I also think I want to try 17.5mm carb on 49cc Super 9. I think 19mm would definitely be too much for 49cc engine stock except for pod airfilter and expansion chamber exhaust. I am still thinking 17.5mm is to way to go for my 1st bigger carb.
I bought a lot of different main jets/ slow jets for the oem carb. I feel like I have it figured out and tuned to the max. I would like to do the same with a larger carb. When I get more info on what to get for tuning a specific carb, I will probably buy something, and just deal with what I have.
Cheers