When i return to the garage, i cleaned the air filter (it was decent sandy), carbs are completely washed and blew with compressed air, rubber membranes sprayed for softness with silicone, tank was cleaned also(HRC mod on fuel tap)etc. I have been assured that a problem with fuel delivery system, but anything from this hasn't brought results.

My numerous rides have shown interesting feature. After the motorcycle doesn't go about 3-5 hours, i can ride normally in a short distance(5-10 km).
Can you advise where to look further?.
