I have a 17hp OHV briggs & straton engine with a new battery & starter. When I try to start it the motor turns like the battery is low. When the engine comes to the compression stroke it bearly turns. On the exaust stroke it turns fast.
Could the problem be the valves needing adjusting ?

Yes both set at .004 - .006 1/4 inch past Top Dead Center Or TDC

Hi,
I agree with the previous answer and the specs given, but would just add this link:
YouTube - Lawn Mower Repair Valve Adjustment
Peace,
Clarke