I just got a .900 sprocket for my project and it hit the inner primary i thought that this was as big as you can run with out hitting do i need to grind the primary to make it fit or what it is hitting around the bearing housing any help would be great thanks in advance

 

If it's just hitting the ribs you should be safe removing a little material there. Leave a gap of at least .060 between the cace and sprocket to allow for heat expansion. If it looks like you are going to have to remove a lot on material then I would go to a .75 offset.