dt 85 i really need help.

[oconnorcal]

i am having real problems with getting my dt 85 running correct.
it constantly backfires through the exhaust.
i have cleaned out the carbs and changed the air fuel mixture and it still backfires.
i have changed the plugs, the middle plug gets a dry black coating on it and the top and bottem have a oil coating on them.
i have took the plugs off one buy one to see if the backfire stops but it dont.
i can have the engine running on even one plug which is the bottem one but as soon as i take that one off with the top and middle connected it wont even fire up.
i know the middle plug has a spark as i have seen a spark while turning the flywheel by hand.
i will upload a video as soon as i can of the backfire and i hope someone can help me as im going nutts!!
thanx in advance.

[oconnorcal]

this is the link to my video. plase watch.
Suzuki dt 85 backfire - YouTube

[boats.net]

That looks and sounds like a lean pop, which is associated with fuel. remove the carbs and verify every fuel/air passage is free of debri. You can do this with carb/choke clean spray. Use the straw and verify the passages are clear. Make sure you link and sync the carburetors and adjust each carb individually (air/fuel screw).

[oconnorcal]

I have already had the carbs off and cleaned. The carbs all open and close in sync and have tried changing air fuel mixture. Still no luck