z1r rear brake drags

hi i have a question i have renewed the caliper seals the pistons are in good order and no crud in the groves rubber grease used i the piston push in easy i filled a bit off the side of the pads so they are not tight in the caliper yet when i spin the wheel the brakes are just binding a bit the same as it did with the old seals in it the master cylinder was all cleaned 3 years ago and i use silicon brake fluid .i was thinking is it because it only relies on one seal rather than two on a modern bike oh and the rear brake is adjusted right with a small play before it pushes the rod ,any thoughts thanks.david

It could be that the pressure relieve port in the master cylinder is clogged. It is very tiny and often overlooked. Seems like there was a thread with pictures about it some months ago.

Some drag is normal so it depends how much drag there is.
To much drag disassemble and clean both cylinders.
 

Here is the thread. In this picture you can see both holes. The tiny one I am talking about is below the larger one.

www.kzrider.com/forum/5-chassis/613477-1...tuck?start=12#829701

wrote:

Some drag is normal so it depends how much drag there is.
To much drag disassemble and clean both cylinders.

 

Yes, indeed. If the wheel is still easy to turn by hand after applying and releasing the brake, it is probably fine. If the wheel is difficult to turn by hand, or it gets progressively more difficult with each application and release of the brake, then something needs attention.

Have you checked the adjustment bolt for the foot lever?
If it is spun out too far it will keep the lever pressed down and prevent the fluid from returning to the  reservoir causing a build up of pressure in the caliper 

 

hi thanks for you imput  its difficult to describe how it feels but 73 z1 comments is a good way to word it ,i thought  it  would turn easy with no drag  with  new seals in it  when i push the pads in further there is no drag at all ,i will have to look into it ,,david

Also, be sure that the lever moves freely. The pivot can collect dirt and rust which can cause the lever to not return properly.

hi texaskz for all your replies yes i restored the bike 3 years ago and it never goes out in the rain i remember greasing the shaft  but i will look into it ,david

a quick follow up to my problem a took the master cylinder apart today and it was all blocked up with the crystalised stuff in there which texas kz  thought ,,many thanks

Glad you found the problem. Let us know how it comes out.