Multi 2015 1200s Brake Problem

An air lock somewhere in the system see if you can get hold of a power or vacuum bleeder there a bugger to bleed.

 

as above, could be many things but one that comes to mind and that is a good sealing faces on all unions/washers. Likelyhood seems higher when people have fitted aftermarket hoses without paying attention to mating faces or correct figure when tightening, have copper washers been used at unions?

 

So question is have you replaced hoses, have the pistons popped out while cleaning etc, any drop of brake fluid levels? If there is air trapped in the system the most difficult area it gets into is around the ABS unit if I remember correctly.

Have you tried the old trick of tying the brake lever hard to the throttle grip overnight, that normally brings most air to the master cylinder which you can bleed easily from.

By the way I am no expert and it’s not really an area to mess around with.

 

I can see we were both typing at the same time. So piston seals could be an issue, it might not even be air, if the pistons aren’t moving freely inconsistent brake lever pressure occurs.

 

If you've no leaks I would still go for air in the system. Leaks become very obvious quickly dampness round the piston/pipes loss of fluid so if you don't have any of these it would suggest the system is sound and you have air in it

 

When you say "no leaks in the system" I am guessing that you mean that you have seen no evidence of fluid being expended? The trouble is that a minute imperfection in any sealing face can allow air to pass but not fluid. I will watch your thread with interest and could p.m. with more detail if you think it might help as yes, there are many other possibilities. Leaks at slaves are more often accompanied by fluid being ejected so usually easy to find.

 

that is obviously wrong but is normal behaviour with air in the system, i.e. - brakes working on 2nd or 3rd pull. Have calipers been working hard and getting very hot/is it possible that one caliper (or both) are partially seized? as this is one way that air entry is inevitable. You will have to take care if front brake not very effective, but you can carefully check by going for (approx) a 2 mile journey at (approx) 50 mph sustained and then stop and immediately check temperature of calipers by hand.

 

It is possible for the seals to allow air in and not let fluid out. Would suggest you fit new seals in the calliper

 

Brembo do not generally supply seal kits for their products. You would need to get the seals out first and take them to a dealer for him to tray and match them. Unless you are 100% sure what you are doing with brakes, I would advise getting the bike to a dealer or a mechanic that is competent anyway.
It sounds to me like you have trapped air in the system. That would explain why the lever is soft at first and then forms up with use....but I have not yet come across a system that leaks air via the caliper seals, but does not allow fluid past. Always a first time mind, but brake fluid when under pressure has a lot of force - it can find the tiniest pin prick and leak out.

 

Have you bled the top of the MC that goes to the reservoir? Mine used to need doing very few thousand both clutch and brake

 

IIRC you can get Brembo seal kits from KTM dealers?