If 3 people own 100 acres can 1 sell any portion. Of land without consent of other 2? Could timber be sold off property without consent

No. Property cannot be sold without the signatures of all of the owners--not even a portion. However one of the owners can sell his "share" of ownership.

If the 3 owners can't agree one or more can sue for partition of the property so it is divided into 3 parcels with one owner each.

Also, in many places it is illegal to sell a portion of the property (thus "subdividing" it) without local governmental approval.

Sell the timber and you will probably be accountable to the other owners for their shares of the proceeds.