Check ebay for an x-tender. That'll raise the seat height about 3 inches. If you still need more then check out minibikesprings.com. We did the x-tender first but we were still bottoming out. The springs made a huge difference.
We also added handlebar risers, took the restrictor out of the exhaust, went 1 lower on the main jet, added boyseen reeds, and then got the biggest rear sproket I could find.
Our PW80 now pulls wheelies in second gear with me onboard and I'm about 210 lbs. Stock motor except the reeds.
Do not buy the staged power up kits for the PW80 on ebay. If you want to know more about those kits e-mail me or send me a PM.