alright i have a 400ex with a lrd full system and a stock carb bored to 38 or 39. my main jet is 170 my i lowered the clip one and i left the pilot at what its at. every time im on the gas and let go it back fires. any suggestions. im going to try and play around with it a little more but what does backfiring mean? any help would be appriciated thank you.