Brake and Clutch Fluid level check

[jfheath]

I Flush mine through every year (18 months max). I'd fill it up to the casting line inside the reservoir regardless of the amount of wear on the brake pads.
This opens up the possibility that when I fit new, there will be no more room in the reservoir - if I just push the pistons in. But that never happens because I never fit new pads without a full check and flush.
I'll fit new pads earlier than I need to if I have a long tour coming up and keep the 'old' set which may be only half worn. Clean them up, dress the surface and stow them away for later use. If a set wears down I may fit brand new or I may fit an older set - depending on how much year or how much riding is left.
Turning the steering to fill up. Oh yes. You usually learn the lesson the hard way that locking the steering in position while the cap is off a prudent thing to do.

Piece of info from my 1100 days - if you push the pistons in and leave no room in the master cylinder reservoir, the first cycle of the ABS motors - they will not be able to turn and the ABS fuses will blow.
The gap is important to allow returning pads and expanding brake fluid some space to return without issue. If you don't, then you could have a brake lock up - which is not the best experience to have with a motorbike.

 

[etalors]

I Flush mine through every year (18 months max). I'd fill it up to the casting line inside the reservoir regardless of the amount of wear on the brake pads.
This opens up the possibility that when I fit new, there will be no more room in the reservoir - if I just push the pistons in. But that never happens because I never fit new pads without a full check and flush.
I'll fit new pads earlier than I need to if I have a long tour coming up and keep the 'old' set which may be only half worn. Clean them up, dress the surface and stow them away for later use. If a set wears down I may fit brand new or I may fit an older set - depending on how much year or how much riding is left.
Turning the steering to fill up. Oh yes. You usually learn the lesson the hard way that locking the steering in position while the cap is off a prudent thing to do.

Piece of info from my 1100 days - if you push the pistons in and leave no room in the master cylinder reservoir, the first cycle of the ABS motors - they will not be able to turn and the ABS fuses will blow.
The gap is important to allow returning pads and expanding brake fluid some space to return without issue. If you don't, then you could have a brake lock up - which is not the best experience to have with a motorbike.

The two mechanically correct responses to this question, that make a lot of sense and in line with best practices are in post #8 and post #41. Thanks to all for weighing in.

 

[SMSW]

I Flush mine through every year (18 months max). I'd fill it up to the casting line inside the reservoir regardless of the amount of wear on the brake pads.

I agree, because pads last me much longer than the flush interval on my bikes. When I flush the brake fluid, I drain the reservoirs first, then add fresh juice. And, since these are my bikes, if I'm meddling with the calipers (removing them, changing pads, whatever), I always remove the reservoir's cover and suck out some fluid.