Most of the times these hiccups occur due to lean mixture, is your bike doing like this while accelaration Brrrrrrrrr, Brr, Brr, and then again when you twist throttle engine resond like this Brrrrrrrrrrr., mean your accelaration is not smooth, if you have to constantly twist the throttle to make your bike go, then mostly it's tuned towards lean mixture, or air is leaking into your AFR, just open your bikes spark plug and see what is the colour of the tip , it should be medium tan, if it's very light near to white in colour then you are running on lean mixture, how much of 2t oil are you adding from the top, you shouldn't go beyond 40ml/Litre, most of the 2stroke owners add oil from the top in the fear that if the oil pump fails they will never know and without 2t oil engine will get destroyed, as i said earlier these pumps are very good and very very rarely fails.

[ATTACH=CONFIG]146216[/ATTACH]

I read the guide about the spark plug, but I do not understand the meaning by colour so please see the pic attached and tell me the condition of the engine.

This is the link of the tutorial I got from this forum somewhere.
NGK Spark Plugs USA

By the recent check Oil pump is working fine. Still I'm adding 20 ml for 1 liter of fuel. Also I like to mention RX emitting white visible smoke and it is having catalytic silencer. I don't know which oil they were adding at fuel stations so I brought "Shell Advance vsx" synthetic oil to add by myself.

That's good if your bike's Oil pump is working fine, as you are adding little bit of excess 2t oil you are seeing this white smoke you could also be leaning mixture by adding more oil,from the looks of the plug it seems you are running lean, the central electrode and the bent ground electrode should be medium to light tan in colour, the outer threaded shell of the plug should be slighly wet.Your plug's central electrode is looking white in colour plus the threads have not got even little bit of oil, which indicates that too much of heat is being generated, whenever you rejet your carburetor or tune it first check your oil to gas mix ratio, adding more oil to your gas makes your mixture leaner and vice-versa.Attaching a pic of finely tuned engine's spark plug.[ATTACH=CONFIG]146232[/ATTACH]

Thank you for the answer in detail. Now I got an idea to deal with this problem. I try something by myself and if it do not workout take my RX to the mech. Thanx xBhp for the great platform especially newbies like me and great helping people here. Thank you @kusmaker for taking time to help me.

Once again thanx and have a great Sunday to the big biker family