I have a yamaha sxr 600 triple in the shop and I'm doing the normal carb cleaning procedure on them . With the carbs assembled and upside down I apply some air pressure to them and they start to leak right away at 3 psi. I'm used to testing them this way on the polaris sleds I work on most of the time.they usually hold at 7psi.Especially the viton tipped ones. Is it common for these sleds to need needle/seats too ? didn't want to spend $75 for them if i didn't need them. Does anyone else offer a mikuni replacement cheaper ?
Biggest problem I've ever had, in my limited experience, is one sticking open after storage before cleaning(crud). I was going to replace that needle and seat the next season and never did, still good to my knowledge. I would say it will probably be fine. Float weight and length of arms will affect the pressure required the way your testing.(I don't know the Polaris carbs at all)
check the float height, they need to be set at 13-14mm from the body upside down. i have seen a few that hit the top of the carb body befor they close the valve. i have never seen a valve bad