you would have to go to a garage and get it physically removed, then you need to get your bike re-registered. but this also depends on what country you live. in countries like Australia you have to do this. in my country (Indonesia) we don't use limiters other than the ones that comes with the bike that only comes in when the bike hits the top rpm.
111
The fuel is inside the hood
Kawasaki recommends regular 10w 30 for the prarie 300
Try eBay.
3 quarts
Try eBay.
Under gas tank passenger side
On most atv's the serial number is in two locations however on a 2003 Kawasaki Prairie 300 the serial number is in one spot. It is located under the frame on the driver shaft.
Biu
As you are sitting on the bike, it is on the left side, in front of the rear shock.
Sounds like dirt/crud in the carb. You need to remove, disassemble, clean and reassemble the carb.
Underneath the engine, in the middle of the shield under the frame there is a oil drain plug.