I laughed my dash off going thru this thread........Eur0_2 ...... mere bhai.........mere laal............teri bike bilkul theek hai...... albatta aap ke baaray mein yeh nahi kaha jaa sakta...... hahhahahahah just kidding! (No offense intended)
Dekho bhai...... ideally when petrol (C8H18) combusts with Oxygen (O2) it produces 2 things........ carbon di oxide (CO2) and water (H20)
2C8H18 + 25O2 --------> 16CO2 + 18H2O
Matlab ideally there should not be any carbon deposits. However realistically its almost impossible to get the air fuel mixture 100% right. Just think of it of what your asking...... you are asking a 80's technology carb to mix exactly 2 parts of petrol with 25 parts of oxygen at every revolution of the engine...... bachay ki jaan lo ge kya.
Mere bhai...... CG loses its crispy exhaust note because of carbon deposits in the exhaust......... several people already have told you that........ its inevitable. Your Spark plug tip indicates the air fuel mixture is right on the money...... it should be chocolate brown in color. Cadbury ki chocolate ka jo color hota hai na..... woh hona chahiye.....jo hai.
If you want the same exhaust note back....... clean the exhaust. Indian filmo mein villain ko dekha hai na woh kaisay apni rifle ki naal ko saaf kerta tha......bas gabbar ban jao........ take a straight rod and roll a peice of cotton on its tip and give your CG a colonoscopy.