luis fradinho

Cheers, Just wondering if anyone can help with the tuning of my RD. The engine was been rebuilt. It seems to work very poorly as it only stays even at 4000rpm with the air intake screws fully in. Would not start unless one of the carbs air intake is blocked. Carb settings are ok, the inlet manifolds and the metalic tube between the 2 carbs seems good too. Some times the carbs starts to leak from the cubes. Changed the O rings from the valves. I've also checked the ignition point. Is it a air leak ? Any help would be much apreciated.