Motorcycle Repair: not running properly, loud bangs, fuel mixture

Question
hey mate,just wondering..i cant seem to figure it out but i have suzuki dr 200 trail bike.ever since i have owned it ,it has had a flat spot in acceleration and been spluttery when i accelerate and it is getting worse i just cleaned the carb main jet but it made it worse now i can hardly accelerate and it is very spluttery unless on full throttle and then for some reason now full throttle seems like half throttle theres no pull. and i just lost all compression when i change down gears to compression brake it doesn't even slow me down and i have a flange blown in my exhaust and it is making a popping sound and loud bangs sometimes when i accelerate and backfiring allot when i try to go full throttle from stand still. sorry for all the writing but i just don't know where to start.

Answer
Sounds like your fuel mixture is out of whack.  Instead of trying different jets etc, it's usually a good idea to make sure everything is as the engine expects; i.e. the air filter is stock and clean, the exhaust is stock and clean, and the compression and ignition timing is normal.  Then it should run fine as stock,  Any deviation, air inlet, air exhaust, etc needs to be tested since it can produce flat spots and less performance.
From your description it sounds like the secondary circuit in the carburettor is blocked.  The main circuit is less likely to.  So clean all the passages in the carb and see how things go.  Good Luck,  Jan