Hi, I’ve just removed the carb from a new to me Factory 4t as I was having problems with it occasionally popping and stalling off idle.  When I’ve removed it I've noticed a rubber bung on a breather pipe at the top of the carb had perished and split.  Two questions: 1- would that split cause the problems I’m having? 2- is this bung normal (it seems too smaller diameter for the pipe?) Thanks for any help, it’s a bit more complex than the 2t carb I’ve been used to!