I just found this site which offers a Carb Kit as a replacement the the stock TK.
http://raptor90.net/parts--accessories.html
I have been talking with the owner and he says the...
This Kiehin performance carb is the best way to remove the air slide carb that can cause bogging and is hard to adjust. This kit comes with the carb, jets, throttle cable, foam air filter. Great performance mod for the money. $200.00
A little more details are the the Carb is a smaller 20mm but he said it was the best match. I am debating if I should use his kit or move up to the Kiehin 22mm. The biggest issue is where to get the cable that matches the carb and will still work with the thumb throttle.