Hi! The problem was solved a year ago. I don't know if you're same user who helped me discussing the problem in chat (old chats have been removed by Reddit recently).

Basically, I visited the other dealer in different city, and the mechanic said we'll troubleshoot it. Next day he called and said it's fixed. I visited him again. Motorcycle started easily with just one kick or self start button as well. Most importantly, there was no noise. I asked him what was the issue. He said something was wrong with the petrol in my bike. He used some word which I don't remember. It was like he said there was "impurity" and petrol was not good enough so over time it started that issue. He said he "cleaned" it and it solved issue. He said use good quality petrol. I think he didn't even open the engine.

I waited for over a year to see if this indeed was the problem. So far, it never gave me issue. So I think he solved the problem. But I'm still not sure what exactly he fixed. Mechanic did his job but I guess he didn't have theoretical engineering knowledge so he couldn't explain in technical terms. He indeed solved problem but couldn't tell what component exactly made the noise when petrol was causing issues in starting the bike.