K75S rear disc not flat - what are the options?

[Glacial]

The rear brake on my K75S is very jerky in operation and when I rotate the wheel with the bike on the centre stand it is clear that the disc binds against the brake pads at one point while rotating freely in between.  Assuming I have to replace the rotor to fix this issue, I then have the problem of what type to get.  When it came out of the factory my brick had ABS but the previous owner had trouble with it and ended up removing the pumps, sensors, computer and pipe work.  Will I be able to fit a non-ABS rotor or do I have to get an ABS one?

[Motorhobo]

My front brakes were grabbing a bit on rotation at slow speeds after replacing the pads causing pulsing when braking. It has all but corrected itself after re-centering the wheel as per the procedure in the link below. I also had issues with the front ABS that were corrected simply by loosening the front wheel and retightening it properly. The front wheel is self-centering, see below...

http://www.motobrick.com/index.php?topic=5252.msg32535#msg32535

I've read stories about people getting new disks and still having the same problem. If you haven't centered the wheel and then loosened the caliper mount bolts and retorqued I'd try that before checking to confirm that your disk is in fact warped. Not saying it will fix your problem, just saying it's worth it to rule out the cheap easy stuff before moving on the expensive fixes.

[pdg]

My rear brake pulses too...

If I remove the wheel and the disc, then clean all the mating surfaces and also the friction portion of the disc (with a mild abrasive) the pulsing is much reduced. Then it comes back after a couple of hundred miles. Also, making sure the wheel bolts are at an even torque makes a difference too - just 'doing them up' by hand is fine, but if you're a little off with torque balance it can put a wobble on the disc.

A new disc may or may not solve the issue.

Oh, and I can't see a difference in the important dimensions between ABS and nonABS discs (I have both here) but that's by eye... The only real difference I can see is the sensor ring.

[Motorhobo]

Oops...sorry, didn't see that this pertains to rear not front...my bad.

[Scott_]

Check your master cyl at the rear pedal for accumulation of crud and gunk that can/could be limiting the return travel of the piston.
Probably not as critical on a monolever 75, but a dragging brake can cause heat/fire issue with the paralever rubber boot.
To the OP, I don't think it would matter about the ABS ring as you say you don't have the sensor installed.
I know for the 1100's the brake disks that are available(at least from EBC) don't come with the ABS ring anyway and you have to reuse your existing one.

[gladstone]

I had similar on my 1100 but the disc/rotor varied in thickness (from 4.98 to 4.94mm). I replaced it with an EBC one where I had to swap ABS ring over which was very straight-forward. I may get the original skimmed and keep as a spare.

Cheers

[Glacial]

Thanks for all the feedback and advice, I'll let you know what I find when I start spannering.