Dear @Challenger
Thank you for your reply, very much appreciated. Actually this morning i've seen the leakage was from the drainage hose located under the carb, it was heavily draining even i could able to see the fuel flow there.
Actually one of those repairmen disassembled the carb but told me that this carb is not rescuable and advised me that he can change it with another kind of (somewhat irrelevant) carb but since the guy's talk was totally cheap, i haven't been convinced by his shitty advise. My perception was that guy didn't know what is doing and gonna fuck up my bike. The rest of the repairmen i headed even did not show any interest and blackmailed yamaha dtr models by claiming that there's no permanent solution for such leakages, they even advised me to sell the bike.
I mean, the thing is that there's no any well proficient an reliable repaiman around so eventually i come up with the solution of replacing the carburetor completely with a new one which might be a best fit. If i go for rebuilding the carb by myself i'm sure i'm gonna mess it up.
Your advise is very valuable, please let me know.