Beam problem finding max bending stress

[Resa]

Alright so I drew it out like did the reactions and everything then I realized I need to include the diameter of the beam. How do I find the max bending stress while using the diameter of the beam? All I need to know is what exactly I do differently compared to drawing the bending moment diagrams with that 2 and 1/2 inch diameter.

 

[Resa]

Without including I got R1 to be 50 and R2 to be 650..

 

[PhanthomJay]

Reactions look good. The diameter comes into play when calculating max stress at point of max moment. Why would the moments be different if the shaft was of a different diameter? Do you know how to calculate bending stresses?