Get some pro wedge tires, they don't last amazingly long on pavement or anything besides sand and snow, but they ROCK. Smoother ride, variable gearing thanks to the massive expansion of the tire at high speeds. and 22inch to start with.
At low speeds they are 22 inches. At high speeds, they could be 25 inches, this is a guestimate.
Maxis 4-snow, pro wedge and i think the ams zippers
You could make the bigger exhaust like your saying. Cut the valves and try putting in some bigger 1s. Don't know how well they would work, but you could try valves from a KLT200 or something. Get a 26mm carb. The KLT200 uses a 26mm, that should be a sign. Mill the head down a hair for higher compression.
I just wanna go fast. If your not first, your last!!
Reproducing the Tecate CDI. Contact me if you need one. I'm most accessible on FaceBook. You can find me on the 1984-1987 Kawasaki Tecate KXT250 Group.