Re-jetting with mods



Im just starting to put some mods on my blaster, fmf pipe, silenecer, k&n airfilter, and people tell me im supposed to re-jet. How do i a re-jet and what do i need to do it. I know how to take a carb off and stuff but i just dont know anything about jetting. Does anyone know specifically what i should do withthe mods listed above.
also i would recomend a oil block off kit if u don't have one, as soon as i started to mod myn and still had the oil injection it only lasted a few months then it needed a start of try a 270,280 main jet to re-jet it..........
Deff get an oil injection block off kit an run premix gas, i would try about a 260 main jet with those mods, once you rejet do a plug chop which means fire your blaster up run it down the road wide open pull the clutch in an shut the motor off right away pull the plug see what color it is if it's white your still to lean on the main jet if it's black an wet you rich if it's a brownish color your jettin is perfect