quad wont start

[atb400ex]

So i was riding in the dunes this weekend,(Buttercup to be exact.) We were riding along the Mexican border. I shifted into fifth, and my bike started ticking up by the oil reservoir, and slowed down considerably. It did that for about 1/2 a mile, then it just died. I got towed back to camp, and we checked my oil, and it barely registered on the dipstick. Everything else seemed to be normal. It turns over, but will not start. We filled it up with oil but it still wont start. Any ideas? Mostly stock 400ex.

[gt400ex]

Cam problem, maybe a head gasket? See if there is exhaust coming out of the tail pipe or air coming out around the head when your turning it over.