znen are chinese bikes and the quailty is generally poor. The chinese may take over the world one day but they have a while to go for motorcycles.
Your plug will either be under the seat. Take out the seat bowl under your seat and you should gain access or there will be a small panel near your feet unscrew and take out. When you change plug be careful when you put it back in. You can easy strip the thread so dont force it it should go in easily.
bb
April 2010