[culcune]

Carb change--Weldangrind could link you to the place on Ebay that sells Chinese-made Mikuni carbs which he likes because of the ease in which to find and change the jets. I think the carbs are under $40.

I believe other things are to use a K&N air filter, and figure out which exhaust can be slightly modified for your bike--both would require jet changes.

There is not much to do with the actual engine. While they are 'Honda-like' they do not seem to accept internal performance parts adapted from Hondas. I would stick with sprocket changes (change the rear, too), carb, air filter, and exhaust (although that would involve modifications).