I just adjusted my valves on a 99 yz. They were getting a little bit tight. The weather here had permitted riding 1 month ago and I was getting some intermittent loud backfiring like a gunshot. The bike would run great everywhere but idle where it was a bit erratic. The weather has not been nice enough to ride since then and so I decided to check the valves. they all seem within speq now but if the choke is on it seems to run ok on the stand but as soon as you take the choke off it will bang and pop and shoot a blue flame 5" out of the exhaust. What should I be looking for as I never ever touched the carb but only the valves. The buckets to the 2 right hand intake valves seemed a bit tight getting in if that would do anything??? thanks in advance for your advice.