I have a Gsxr 250RR if you take the tank off after a while the bike starts, revs up, and idles properly. the moment you put the tank on or take it for a ride about 3km the bike dies down and battles to start if it does start you can full throttle it and it will just about idle?? i have absolutely no clue what could be causing this neither does the bike mechanic ... we have cleaned out the carbs about 3 times changed the plugs, flushed the tank and adjusted something with the valves and changed the coils. nothing

Thought it could be something with the air box been squashed by the tank cause when you spray air into the air box with a compressor the revs come right up again

So we tried putting on some individual air filters for each carb and it works for 3km then back to not revving

The next step i think is changing the cdi (could this cause it?)

PLEASE HELP