When i first installed my new exhaust system with the Trenga carb, It started right away, but i didnt leave it on for so long because i didnt have any oil at all in my engine. so i dont know what the problem is. try checking the jets and floats, you should also clean the inside of the carb with carb cleaner and a high-pressure air gun (like the ones that go on compressors) to take out all unwanted dirt that might be hiding inside those little holes.