Master cylinder not pumping.

Easy!! They do sometimes end up with sediment in them.

 

Hi there, Ron, I thought I was going to have to re-seal my Tiger front master cylinder when I had similar symptoms after cleaning the pistons and replacing the pads. I bled and bled the lines without success, then I read about taping the brake lever to the bars and leaving overnight. I used a zip tie, left it for 24hrs and low and behold the brake lever was as solid as a solid thing thing on tough day - front brake now works better than ever !!!!!

 

Can't remember Ron as I did it on another one of my bikes a while back but I find it one of the more easier and enjoyable jobs. I use those little ALDI pointed hook tool kits for rubber seal removal as they leave no damage.

 

I'm pretty sure it was Capt. Who posted this method a few weeks ago.
Sounded illogical but apparently worked.
Another mystery for Arthur C. Clarke

 

Had a problem bleeding the front brakes on a Bandit with ABS a couple of years ago. No amount of bleeding could get rid of the air. The solution was just to leave the lid off the master cylinder reservoir overnight. Twas perfect next day.

 

It's hard to see how air got into the system or how master cylinder seals would get damaged. Used to have a lot of bother with KTM enduro brakes. Just an idea but if there's air in the system it may be in the slave cylinder. Used to put pressure on the piston and open the bleed nipple thereby forcing any air out of the cylinder. It's not always successful as air can be forced back into the pipes. Also clamped pistons fully back and bled again. Sometimes worked.

 

the brake lever piston hasnt dropped out got damaged in the handlebar assembly or the switch set not working?

 

"Anybody ever stripped a master cylinder to change seals? Easy or hard?"

It's normally fairly straight forward. Remove lever, rubber boots and link pin. There's usually a circlip that once it's removed will allow you to remove the piston assembly. It may be stating the obvious but the fluid reservoir should be drained first. Worth getting a diagram of your particular bikes mechanism but there's generally not that much to them.

 

If it was working okay before the pad change, it is very unlikely the master cylinder has just packed in.
I would be looking at getting rid of a serious air lock, full system drain and new fluid.

 

Yes it's sounds like a surgery job Ron

 

Hi MrO,
Where are you getting no pressure ? @ the lever ? If so and you are getting no air out of the bleed nipple ? Try pushing the piston fully in on the caliper and then bleed it, if that doesn't work you probably have some dirt near the bleed nipple (internally) this is what maybe stopping the air escaping.

Cheers capt.

 

Try slow pumps, bleed M/cylinder first, by loosening the banjo/line out. Do all banjo/joints working down to caliper ! Oh is caliper stuck ??? Dirt could have worked into the area ! First bleed/pump of M/cylinder piston moves out. Doesn't return !! Gives symptom. No Presure @ lever/Master cylinder !

 

Sounds odd, can't really see how you can do any damage pushing the seals in, unless you caught a bit of grit and damaged a seal, but then you should be able to see a leak. I'd take the calliper and pads off again and check the pistons move freely and there are no leaks. I guess it has to be air in the system or a leak really, not much else to go wrong.
I had terrible problems once with a speed triple, somehow sheared off a tiny piece of the seating surface at the bottom of the bleed nipple hole. I took the bleed nipples out to clean them and can only assume I managed to pick up a bit of grit on reassembly, definitely not overtightened, and the damage indicated something caught on the seat, like a tiny nick. Also, could not get the banjo washers to seal, always had a tiny bit of fluid if you held a bit of tissue paper against the outside. My mate suggested annealing the copper washers first and that stopped it straightaway. Have bled loads of brakes and this was the only time I have ever had any problems. If you have got air in the calliper, then using a syringe to inject fluid in via the bleed nipple can help.