I can and did lol. Not sure what happened either, I only know basics.
Regarding the fuel cap I doubt that is the problem. The cap is there for only 2 reasons, to stop fuel slopping out and sh*t getting in. It does not seal 100% so as when the petrol is used the space is replaced with air.
It is sounding heat related. As the engine and other parts warm up they expand. When this happens existing gaps can increase and new gaps can appear. Sort out the leaking exhaust and check all the carb rubber connections. Also do the carb rubber test as this will check for leaks and perished rubbers.
cheers
KK
