Or tell us what you're trying to do.
But I'll make a guess: Are you trying to divide the system clock frequency by 6400 and output the result on a pin so it is observable with a scope? Not sure why the interrupt would need to be enabled.
If so, try using compare match by setting TCCR1A appropriately. The resulting signal will then be output on the OC1A pin (Arduino pin 9) or IC1B (Arduino pin 10).
Don't assume register values are the initial values as documented in the datasheet, as the Arduino core does some initialization for PWM, etc. So if I want to use the timer for my own purposes I usually start with
TCCR1B = 0; //stop the timer
TCCR1A = 0;