And allow me to add: it is much less of a problem to plug up the exhaust vent for several reasons, usually internal pressure will overcome the vent's ability to stay closed, and there are other ports that will provide the venting process as well long before it becomes catastrophic (such as the entire spring loaded fuel cap sealing plate will simply lift- sure it will stink for a bit but it relieves the pressure).
On the other hand, plugging in the intake vent is often catastrophic because that often results in an entire vessel failure, always of course, depending on how long that vent is plugged.
But on a serious note, the most common method by far of fuel tank failure due to vent failure is collapse (the tank caves in). The reason is simple physics; on a fuel injected vehicle, the fuel pump can get quite close to a full vacuum inside the tank which makes for a 14+ PSI differential. It is not possible to build up 14 PSI inside the tank given nothing but gasoline expansion unless some ridiculous event happened such as you fueled the bike in Dead Horse, AK, at -60F, immediately put the bike in a plane and flew it to Death Vally, CA, while it was 125F..... and even them I do not think gasoline has the ability to form that much vapor pressure. But of course I could be wrong and so we better just wait for someone to do this and we will have actual results.
Brian
heh HEH He said butter and squealing.
Yeah, screwing up the escape vent isn't for everyone.
....same goes for the intake vent, but the latter is one of the more popular options.
..sorry folks, but someone just had to show why all those "easy boys" are justified, and I'm just the guy for the job. Thanks max' for the assist.