TW-87 and I did a pretty good job of hashing out tuning the old style, round slide carb on the pre-2001 TW on the old board. This is NOT the CV carb that's on the '01+ bikes.
https://tw200forum.com/forums/91793/ShowPost.aspx (not working right now...)
and PJungnitsch had good results bumping up his pilot jet here:
In a nutshell, the old carb came stock with a 114 main jet, at least it did in North America. TW and I both had fairly severe pinging we were running so lean -- I also had major problems with surging and cutting out at high RPM. The bike would struggle to get much over 55mph.
I experimented with every step between the 114 and 124 size main (OEM Yamaha jets). There's a terrific list of part numbers here:
288-14343-57-00 is the stock 114, each time you increment the '57' in the part number by 1, you go up a size on the main. i.e. a 288-14343-59-00 is a 118 main.
In the cold of winter, I was best off with a 120, but that got too fat with the heat of summer. I've since backed off to a 118 and it's working really well for me in the 100 degree heat I'm in on the ride home from work. Runs smooth, revs out, and I'm getting ~65mpg (US). On flat ground 70mph is about where it tops out with a 15t front sprocket. FWIW, I'm at around 700' elevation.
I included the pilot jet thread because I may still experiment with changing mine as well. I'm at around 4 turns out if not a little more, so next time I order parts, I'll probably go ahead and order a 42 jet and try it out. It works fine now with the stocker, starts on the first kick, but I'd feel better with it ~2 turns out vs. 4+.
Anyway, I'll try to add more detail to this post if it needs it, hope that helps -- most of the carb tuning discussion on the old board (and most likely on the new one with time) will center around the new style carb on the '01+ bikes since that's what most people have these days.
FYI - All the info in the old posts and this one are for an otherwise stock TW (stock airbox, exhaust, ignition).
'07 Bandit 1250SA