KTM Duke 390 Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter · #1 ·
Over the last few days the rear brake hasn't felt quite right. I've bled the brake, as I've done before, but now I can't get any brake pressure. I've taken the bleed valve out and put my finger over the hole, then tried the brake pedal. I can feel some fluid pressure on my finger, but the pedal still goes all the way down.

I'm thinking it might be the master cylinder so have ordered another one. The only problem is I can't get at one of the bolts holding the cylinder on. Any thoughts on how to get at this?

The only other concern is, when I pump the pedal I can hear a noise that sounds like it could be coming from the abs pump. Could that be the problem? Is it normal to hear anything from it when pumping the pedal?
 

·
Registered
Joined
·
27 Posts
Not normal to hear anything when you press the brakes. Possible air in system. How old is the fluid in there-is it dark in colour? If so I would change the fluid completely. You can google how to do this withh ABS bikes but sometimes it is dealer only operation I think. Wierd one for sure brother.
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #3 ·
Not normal to hear anything when you press the brakes. Possible air in system. How old is the fluid in there-is it dark in colour? If so I would change the fluid completely. You can google how to do this withh ABS bikes but sometimes it is dealer only operation I think. Wierd one for sure brother.

The fluid is new today. I've done it before and not had any problem, but this time something has gone wrong. Maybe it is air in the system and I'll need to use a pump.
 

·
Registered
Joined
·
407 Posts
My 16 did this....not the noise, but I would bleed it and within a week had no pressure again. Got tired of it happening and bypassed the ABS module for the rear brakes, hasn't happened since....
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #5 ·
My 16 did this....not the noise, but I would bleed it and within a week had no pressure again. Got tired of it happening and bypassed the ABS module for the rear brakes, hasn't happened since....
Funnily enough, I was thinking I might do the same, even just for diagnostic purposes
 

·
Registered
Duke 390. Surprising huh…..
Joined
·
363 Posts
There is a tip that works, use some tape or similar to keep the front brake gently pressed over night. Air in the lines can then escape into the reservoir on the handlbars. Glad you got brakes again though buddy!
TOP-TIP !

I've got a very heavy-duty stretchy rubber band type thing with a removeable connector on it; that i use for the same.

It's surprising how periodic use overnight or over a weekend holding the lever squeezed on; can get rid of any air bubbles in the fluid (How do they even occur on a closed system ???) and solidify up the lever feel.

****A block of 'wood' jammed in between the brake pedal and the seat frame overnight does the same on a car (y)
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #10 ·
One thing I'm still unclear on is, when I do need to, how to get the master cylinder off. There's a bolt at the back that seems almost inaccessible. Any ideas?
 

·
Registered
Joined
·
407 Posts
I'm having the same rear brake problem; how do you bypassed the ABS module?
I pulled off the tank to get the ABS module and removed the rear brake hoses (bit of a pain) & plugged the holes with sealed banjo bolts to prevent residual fluid from dripping from the module. Then ran the shorter of the two hoses directly from the rear master to the rear caliper & bled the system with new fluid. Has not had issues since, and I can lock up the rear tire with the brake :cool:
 

·
Registered
Joined
·
407 Posts
1 - 15 of 15 Posts
Top