1981-1984 Official Honda ATC250R Shop Manual, Page 26Get this manual
MAINTENANCE
ATC 250R
Be sure the brake pedal is properly adjusted (page 2-13)_ Turn the adjusting nut at the brake cable end unti the clearance between the arm joint and arm is 0-1.0 mm (0-0.04 in)Minor adjustments can be made by loosening the lock nut at the lever and turning the adjusting bolt
INDEX MARK
BRAKE WEAR
Replace the brake shoes if the indicator plate aligns with the brake panel index mark when the rear brake pedal is applied