1) foreign matter in the lines. old fluid, water or rust cause blockage and/or corrosion and may not allow fluid to go back properly. Bleed lines with copious amount of new fluid. Never reuse old fluid or put back in a brake fluid bottle. 2) bent rotors - pretty common on quads. replace (bang back as required if you can) 3) caliper not returning. remove, clean, inspect replace.as required. The rubber sleeve that the caliper pin runs back into may be full of crude.
Answers & Comments
1) foreign matter in the lines. old fluid, water or rust cause blockage and/or corrosion and may not allow fluid to go back properly.
Bleed lines with copious amount of new fluid. Never reuse old fluid or put back in a brake fluid bottle.
2) bent rotors - pretty common on quads. replace (bang back as required if you can)
3) caliper not returning. remove, clean, inspect replace.as required.
The rubber sleeve that the caliper pin runs back into may be full of crude.