If it has been sitting for 4 years, do your due diligence and clean and flush the tank, fuel petcock and carb. Inspect and clean the points if needed. Adjust the idle and see if it will idle properly.
If it still dies after the minute it's could be a bad condensor.
Drain and refill the tranny with ATF type "F". 1 speed tranny (round side cover) with 5.5 ozs of ATF. 2 speed takes 9.5 ozs. (retangular side cover) DON'T top it off or overfill if it is a 2 speed.
Go over the bike and make sure everything is properly tightened down and the drive chain is adjusted correctly, not too tight and not too loose (chain slap).
After all this and it runs OK but stll makinga clattering sound and low rpms, then report back.