Roast corn at 350º F for 10-12 minutes, until it begins to char.
While corn is roasting, cook bacon to desired doneness. Cut into bite sized pieces and set aside.
Halve the jalapenos, cutting length wise. Remove the stem, core out the middle - including seeds, and set aside.
Remove cooked corn from grill, cut corn kernels off the cob into a bowl, and set aside.
In a large mixing bowl, combine cream cheese, cheddar and pepper jack shredded cheeses, sour cream, tajin, taco seasoning, and diced onion. Mix well.
Next add bite sized pieces of bacon and corn. Continue to mix ingredients.
Scoop mixture into hollowed jalapeno halves, filling each piece.
Place stuffed jalapeno halves on the top rack of grill or near indirect flame, cook for 15-20 minutes until cheese melts.
Remove from grill, set aside to cool, and enjoy!