The engine will run for 30 mins then cut out.

Year make and model, and are you loosing power to the coil when it will not start ?

hi do you still have thee metal case around the spark plug cap? if so remove it with a pair of plires as when wet the spark will earth out inside the cap, if the problem persists unscrew the cap from the lead
try earthing it out and check here for aa spark, paul

Check for spark first. If spark is there, chances are the carb has filled with water that has accumulated from condensation in the gas tank. Drain the carb, stick in a fresh spark plug and then give it a try. Please rate my answer. Thanks.

Sounds like you have a fuel delivery problem. First check to see if there is a inline filter from the fuel tank to the carburators that is partially plugged. If not, you will have to remove the fuel valve from the fuel tank and clean the screens on the fuel pick-up tubes. The only other thing that would cause a fuel delivery problem would be the vacuum line from the carburators to the fuel valve has a split causing insufficient vacuum to open the fuel valve.

last year my aura classic 110 has same problem like your at first i thought that my coil is busted due to the symtoms that the engine died after a minute of running then runs again after it cools down, when i test the coil the coil if fine so we decided to open the motor and there we saw that the oil pump is brocken, the oil didnt get high enough and make my engine overheated making my engine stop, i know that we are talking at diffrent kind of bike i just giving my point of view and i hope it help

spark plug buddy try new ones and get back to me

A.dirty fuel line/filter/trash in carb B. bad coil C. carb too rich/carboned out spark plugs.D. short in the switch wires

No the fuel pump will not fail more than once. When a fuel pump goes out it just goes. Will not work after that what so ever. Sounds like bad gas lines. I had this problem. I replaced my old gas line after the old one cracked when I did this I cut the new on to long. When I put my tank back on the old one pinched. It would run fine for a few min then sputter and die as the gas in the line ran out. I let it sit for a min and more gas filled the line and would start the process over. Try replacing the fuel lines and make sure they are cut to the right length and do not kink when the tank is on. It could also be a dirty petcock. I had let my bike sit for 6 months while in another state and the gat tank got dirty somehow. I got it running and same problem putters and dies. Neighbor took out the petcock and used an air hose to clean it out and it worked like new.

what kind of machine?

Replace crank sensor. Next time it cuts off pour or spray water on it, to cool it down and if car starts that is what it is. I did this to get my car home to fix it. Next thing I would look at is the coil module if crank sensor does not fix it.