Some times my bike will miss and back fire though the carb is this due to to bigger a main jet
dose not happen all the time just down low on the gas ok

If it back fires then l would suggest your timing is possibly not bang on. How often does it do it? It can be set up properly to sort the issue.

more than likley you have dirty carbs. if it was running fine than sat for a while and now does it they are probably dirty.

SOUNDS LIKE YOU MIGHT BE STARVING FOR GAS,CHECK THE GAS FILTER OR FOR A RESTRICTION IN GAS LINE.TIMING COULD BE AN ISSUE, BUT THAT WOULD BE A PROBLEM NO MATTER HOW MUCH GAS YOU GOT.CHECK FOR VACUUM LEAK, AND CHECK YOUR AIR FILTER.BOTH OF WHICH SHOULD'NT MATTER ON GAS LEVEL.

It could be dirt on the inside bottom of the fuel tank. As the fuel level drops it tends to swish the fuel & dirt around & deposit some dirt in the carburettor float chamber and, consequently, some will ocasionally block the jets & stop fuel getting into the venturi to mix with incoming air, It is worth giving the tank & carburettor jets a good clean and, if possible a compressed air blast into the tank & the very small holes in the jets. At the same time l would recommend cleaning or replacing the filter(s) in the air cleaner

The bikes running lean. Your thinking it does it low on gas? Its probably doing it then cause you been riding and the bikes running hot and leaning out. You probably have an intake leak, spray the carb boots down with some like carb cleaner or wd-40 and listen for the idle to drop right away. If it does its the boots.

Back firing through the carb, too lean.
Back firing through exhaust, too rich.

how come nobody answered tight inlet valve?