Front brake .

[Just grumpy]

OK idiot time, I left the disc  lock on and rode away  . The bike went down hard on the right side, any way went to ride away and had no front brake but it would pump up the pressure I've checked for leeks none found I've bleed the brakes 1 1/2 ltrs great pressure but as I turn the front wheel the pressure drops.
I've had the callipers apart I've even bought a master cylinder and it still doing it. Any ideas.

[Rixington43]

You say the pressure drops, do you mean the lever pumps up firm and then you ride/roll the bike and the lever goes to the bars again but will subsequently pump up firm once more?
Sounds like you've bent the disc and, as the bent portion passes through the caliper, it's pushing the pads/pistons back which is giving you a long lever again. If you can get the front wheel off the ground then spin it and looks for warp in the rotor.

[Just grumpy]

Hi discs are fine no warp, great pressure but move the bike forward or back even 1 foot the lever comes back to the bars.

[Joe Rocket]

If there's no problem with the master cylinder (new) and the disks aren't warped then have you taken the pads out and checked the calipers thoroughly?

It shouldn't take 1 1/2 litres to bleed the brakes, maybe 200cl to be thorough. You have a leak if you lose the pumped 'stiffness' so easily, imho. Could be a seal or even the brake lines.

Edit: Or still air in the lines......

Edit 2: Have you bled the brakes properly? Sorry, I have to ask.

[Rixington43]

Is moving the bike essential to the problem manifesting?
If you pump up the lever and then walk away for 10mins with the bike stationary, does the pressure still go?
If so and you can't see any leaks then I would suspect master cylinder seal, it may have taken a huge pressure hit if the bike went down on the front brake lever. You could leave the reservoir open, keep repeating your pump up and pressure drop and see if you lose fluid, if not then master cylinder.

[Rixington43]

Sorry just seen, did you replace the master cylinder already?
If so then do the reservoir test and see if you're losing fluid.

[Just grumpy]

Joe rocket ,Brake bleeding was done the old fashioned way, going to strip the callipers down again I've possibly missed something simple. I left the lever tied back over night to see if any more air bubbles come out. Thank for all the replies.

[Joe Rocket]

I don't mean to bring into question your abilities but 'the old fashioned way' isn't very technical to me. If there's been a big shock to the front end then there might be an air pocket in the lines (and I hope the lever trick might solve the problem). Tighten the line banjos if you haven't already. Logic says you've got a leak or air in the lines.

Just to back track. You had the disk lock on; which side? I assume the disk lock came up and struck the caliper then?

[kwackboy]

Double check the discs again because if you rode off with your disc lock on its almost guaranteed you have warped the disc.

Raise the front wheel, remove both front calipers then, spin the wheel .

It doesn't have to be massively warped to cause the symptoms you describe.

[purplebikeunicorn]

Change one variable at a time. Bike up on the centre stand or a front stand, pump the brake up and leave it for 10 mins to prove that it's not just leaking down by itself. Then pump the brake back up, then rotate the front wheel through a couple of revolutions, do you lose your lever then?

If the discs aren't warped, have you damaged a caliper bracket? Do they look like they're on straight and holding the pads flat against the discs?

[Just grumpy]

Well I'm a blind auld git, took the wheel off last night and took it to a mate who has a wheel jig thing ( he restores auld bikes) and I have a warped disc looks OK when spinning it on the bike but it's out anuff to ( as has been pointed out to me on here) push the pistons in . So new discs ordered.  Big thanks to all you who answered.  And time for me to get glasses.

[The Doctor 46]

No mechanical knowledge or advice from me  but after pulling away on a 50cc scooter once with the disc lock on and falling to the ground in front of a load of cheering workmen, I have always used a line from the lock to the handle bar ever since. When the line snapped a month ago I chose not to use the lock until I replaced the line two days later. 

Glad you have identified the problem with the help of the clever lads here. 

[Rixington43]

Glad you got it sorted, rotors aren't cheap but you'll not do it again in a hurry.
The forget me not coily cables are a great addition, I coil mine round the clutch lever but the missus passes hers over the starter button so it's impossible to miss before pulling away.

[Just grumpy]

Discs were £250inc delivery for both from Suzuki, daft bit is I normally use a chain but left it in the garage and the disc lock was under the seat. Won't be making that mistake again  .