Change Rest or Master Pose for Character Skelton?

Can you answer this for me. I have a skeletal mesh character and it is attached to a bike via physics constraints. On begin play the Skeletal Mesh simulates physics but instead of his hand going to the handlebars they just stay in the t-pose.

I have exported the mesh into blender and change the master or rest pose to a pose where he is on the bike with his hands and feet where they need to be and it works perfect but going from UE4 to Blender and back again somehow messes up the physics, something with the bones, the guy looks like jello.

I have read that other have had this issue. Anyway, long story short is there a way to create a pose in UE4 and then in the construction script set it up to use the pose in the BluePrint?