A tales of two ATVs 

I bought a “GIO Beast” new a few years ago (Video of a similar one)

In stock form it has many deficiencies:
steering darts left and right excessively
front “shocks” are not real shocks, just stiff springs with shock like appendages
rear coil-over shock isn’t adjustable
slow
rev limited
seat bracket breaks easily, letting the seat shift around while riding
axle bearings are substandard
swing arm bushings are substandard
carb is too small and has issues
fuel line degrades and apparently flecks into the fuel
tank sometimes has welding gunk in it from the factory
no fuel shut off valve
tank doesn’t have a petcock, so reserve fuel is not available.
rack behind seat doesn’t fit exactly
exhaust is apparently restrictive

Solutions!
steering – fine tuning is apparently the way to go here. If I can’t get it good enough I’ll just fab a new a-arms to introduce some castor to the front suspension
front “shocks” – probably modify shock mounts to allow some cheap real shocks from a Japanese ATV.
rear shock – again, probably adjust mount to allow a cheap adjustable shock from a Japanese ATV or bike.
slow – Port exhaust manifold / exhaust pipe meeting point, mikuni carb, “performance” cdi
seat bracket – custom bracket
axle bearings –
swing arm bushings – Yamaha part ???-???-?? is apparently a perfect replacement and of much better quality
carb – replace with “Mikuni” carb from ebay
fuel line – replace complete fuel line with fresh from auto parts store
tank – replace with plastic tank with petcock + reserve from a Japanese ATV
fuel shutoff valve – tank replacement with petcock
rack behind seat – use superman like strength to bend metal to fit
exhaust – buy cheap bumble bee type exhaust, $30 or less.