Do all the other electrics work, indicators, horn, main lights, stop light ? If so then I would say the problem is somewhere in the kill switch wiring or maybe something is grounding to earth, a wire with broken covering, or even a block connector that has corroded. If possible gently separate the connectors and put some WD40 or equivalent water dispersing spray on the connections. Be careful if cleaning them. search Google for the best method. Release all the clips holding the loom close to the frame and see if any wiring is damaged. You can also check the actual kill switch on the handlebars
Hope this helps
Your written English is very good
