You should definitely have an o-ring in there. I'd be worried about gas sloshing out while you ride if you don't have an o-ring seal. Can you say FIRE CROTCH?

xr50racer said:Ill give you a little story about BURNING BALLS
I race Jet skiis. Runabouts which are a sit down type..... Sea doos,
Well anyways when your in the water in the summer your in board shorts...
....