confusing brbrake problem

[stangman]

ok here`s a good one that has foxed everyone i`ve asked, when cold my brake lever has a lot of travel ie almost back to the bar, but if i leave the bike out in the sun there is very little travel, also if i pour a kettle of hot water over the o/s front caliper it again has very little travel. the only explanation i can come up with is that the pistons on the o/s caliper are retracting in too far and heating it up causes the fluid to expand and push the piston back out.

[CaNsA]

air in the lines / trapped in the master cylinder.

always bleed the brakes while the bike is on the side stand.

[cargo]

I'm not surprised everyone is foxed........................I defo am.


kettle of hot water poured onto the brakes