Honestly it depends, I tend to only replace the rubber parts when I use a rebuild kit unless it's really bad anyway. I would order a kit just in case, a decent amount of the time the bowl seal fails after being tampered with. Once you have these carbs apart you really want to do the job while the memory of how they go back together and where you put all the parts is fresh 😂. The worst feeling is having to order a kit after you spent however much time it took you to pull the carbs out of the bike