pvduke
Husqvarna
Pro Class
don't hyper extend pistons. clean w/ brake kleen and a soft tooth brush to remove deposits then block the pistons retracted when caliper is off the bike.
never push pistons back into caliper with desposits on them.
also- i went to overhaul a MC on a 93 YZ this weekend. the bore was pitted so i trashed it. i swapped with a MC from an 85 xr500 that was on the ground behind my bench. i cleaned it topped it off, bench bled it, installed it and it was good to go w/o any bleeding what so ever in less than 20 mins. rode it 3 hours this weekend. worked perfect and has a larger resiv., too. i've done MC swaps in the field and on the track like this more than once, due to crashes, with good results.
non-ABS dirtbike brakes are very, very simple hydraulic machanisms. there's only a couple moving parts in the whole system.
when changing something bench bleed it first and when hooking it up to the hose keep both ends topped up w/ fluid and you wont even have to bleed the brakes. if you are sure you have gotten all the air out and still have lack of firmness issues at the lever then you have a bypass in the master cyl. (spongy hoses are rare and very obvious to the naked eye). you wont have an air leak 99% of the time w/o a fluid leak due to the pressure differential the master generates 20-30 times more than atmospheric pressure.
never push pistons back into caliper with desposits on them.
also- i went to overhaul a MC on a 93 YZ this weekend. the bore was pitted so i trashed it. i swapped with a MC from an 85 xr500 that was on the ground behind my bench. i cleaned it topped it off, bench bled it, installed it and it was good to go w/o any bleeding what so ever in less than 20 mins. rode it 3 hours this weekend. worked perfect and has a larger resiv., too. i've done MC swaps in the field and on the track like this more than once, due to crashes, with good results.
non-ABS dirtbike brakes are very, very simple hydraulic machanisms. there's only a couple moving parts in the whole system.
when changing something bench bleed it first and when hooking it up to the hose keep both ends topped up w/ fluid and you wont even have to bleed the brakes. if you are sure you have gotten all the air out and still have lack of firmness issues at the lever then you have a bypass in the master cyl. (spongy hoses are rare and very obvious to the naked eye). you wont have an air leak 99% of the time w/o a fluid leak due to the pressure differential the master generates 20-30 times more than atmospheric pressure.