Irks, Cams , Cam/Valve springs , 143ml-146ml-150ml Bore kits , High compressio (high top) pistons , Lightweight oil slingers , Valve brether kits , Adjustable CDI ignitions, performance igniton coils , Big bore pipes , 5 plate clutches , Hydraulic clutches , Carbs , Air filters etc
All availible from ebay , just search search search and you'll come across more parts than you will ever need.
I reccomend
-Dhz mini moto
-Dirtpro50s
-Ozmini (ebay user name and store)
-Kaos50 (ebay user name and store)
Start with a carb and decent filter and go from there , jet the thing. Stick a decent throttle ( Domino) and cable on it (Kitaco). Take to the mainfold with a dremel and clean up the rough castings and smoothen out those ports. Stick a decent unristricted pipe on it after you have rebuilt the muffler with some decent packing. That will get you a few more ponies. Get some decent gearing on it by always changing the front sprocket first. Pull down the top end ( or go nuts and strip the motor if you are know what your doing) and rebuild it to spec using better components.
Another couple of handy site I use are from offshore and sell parts we dont get in Australia these are:
eBay Store - Zongshen performance: Performance parts, Appearance and beauty, Hausmotors
eBay Australia Shop - Ultimate Moto Accessories Shop: Bike Engine Styling, Controls, Carburettors Manifolds