front tire issue

[gwcrim]

I have a TTR 125 Yammy and the front tire keeps pulling the valve stem out.  Seems to only do it when my kid or his friend ride the bike.  Ya, they're a bit aggressive but in 4 decades of riding this is a first for me.  Could a loose/worn bead on the tire allow this to happen?

[greencannon]

does it have a bead lock ? if so maybe it came loose or came apart inside, maybe tire underinflated, maybe kids are riding more aggresive than you thought (doing stoppies)
I occasionaly pull stems on my front tire under extreme hard braking, but Im also trying to slow a 60hp beast down. Never had that problem on a small ride like that