Battery not holding charge even after replacing several parts?

I am having tough time for past 6 months with my motorcycle that has battery charging issues. The battery gets fully discharged even when the bike is being ridden, leaving the horn and indicators dead. I took it to service centre and they have replaced the battery thrice, regulator rectifier twice, wiring kit and stator. But the problem still remains unfixed. My bike is a 2005 model Hero Honda splendor (100CC, 4-Stroke). I noticed that this is the first time that I am using dry cell ( maintenance free) battery. I wonder if my bike is only capable of properly charging flooded battery that I was using earlier without much problem.
Added (1). The mechanic told me that he has checked the vehicle thoroughly but couldn't find the exact cause of the problem. I took it to another service centre of Hero honda but they too failed to identify the problem. They have now temporarily given me a wet cell battery to see if things improve.

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