i have a 1995 xr600 , when it starts it idles fine but randomly shuts off and i have to keep on the revs so it does not shut off sometimes it will idle fine for 5 mins and other times it only last 10 secs and randomly shuts off .it sounds like its backfiring through the carburetor it does not do it as much once warmed up but still does it.. my guess was the inlet valve might not be sitting properly and sealing completely, but not too sure, will pressure testing the combustion chamber be a good spot to start and was just wondering if anyone has any advice on what it could be and i would really appreciate any help thanks

could be auto decomp mechanism

bad kill switch. yes they can work intermittently/randomly. I chased this same problem for weeks and took the whole bike apart. Two seconds to unplug the switch and never happened again. Does an XR even have a kill switch? lol

haha yeah it does have a kill switch, might look into that aswell, is there a way to check the auto decompressor is slipping?, my decompressor lever has been taken off my bike though