Back brake dragging

New to the KZ world. 1977 KZ1000.
  Back brake drags constantly.  It’s like the outside puck has no where to retract.  Anyone else encounter this?  Remedy???

unknown maintenance. a rebuild seems prudent. caliper kit. brake hose. fresh brake fluid.

As Vindicator mentioned! This is a common issue with these opposed piston Tokico rear calipers. Used in similar variations between 1977 thru 1980. The pistons were hard chrome plated, chrome rots off and bits bind in the bore. There are two different 43mm piston styles, plain and insert styles. Being you have the 1977 it's just the plain style, nothing fancy. Also once you complete your rebuild, if bores are adequate, DON'T tighten-up brake pedal freeplay too tight!! Too tight and master piston won't return plugging up relief hole.       

BTW, Love it! Nice and clean!!

Here's an Exact duplicate of what you'll be seeing and some tips for removal of a Wiley stuck outboard , or inboard piston. Inboard requires a bit more and can elaborate if air doesn't work. What is often the case is the bores get pitted severely whereas piston to casting clearance gets out of wack. But ya won't know till you remove, might be pristine? Anyhoot, remove the caliper off axle and separate halves, two allen head bolts. Put a piece of shown material cut/drill clamping hole      to equalize spacing and shut off fluid flow to inner piston. Pump your pedal, piston will walk out. Grab some ole towels it's going to get messy ha.    

Can I add that a blocked relief port in the master will also cause "drag"

Wookie58 wrote:

Can I add that a blocked relief port in the master will also cause "drag"

Yep, had that on my ST at the front. Worked fine for a bit then dragged. Easy to diagnose, crack the bleed screw, does it get better?

This can be really helpful in removing pistons from the caliper.

www.kwick.biz/product/kwick-brake-caliper-piston-pliers/

That would be a handy tool Texas, as long as the piston isn't "stuck"! That tool would be handy for calipers that have been detached from master but still somewhat functional. You would be wasting your time tugging on a stuck one. Why toil tugging and swearing, just gently "push" these pistons out! Here's my go to, removes even the most stubborn assemblies. A couple dedicated grease guns and their Grease fittings/zerks. One 10mm, one 7mm. The 7mm is a modified ole original bleeder soldered to a length brass tubing, for clearance issues, soldered to a zerk for the grease gun. The 10mm is just a screw-in for banjo hole. No swearing, just pump. Could be relief hole "only" but wouldn't explain why inboard piston is free but other outer is bound. Have also often found on these, crap can build-up within the line from master to caliper. I would pull everything if it were mine..just saying.   

    Some additional info if it helps. Relief hole in master location, underneath that big-o-17mm nut and copper washer. It's where the wire is sticking out. I always chase that hole with, in this case, a #76 fractional bit. And check that rubber bellow if it's soft and gooey or cracked/hard while you're in there. It's part # is 43024-003. Your 1977 is the first year of this style 5/8" master cylinder and should be anodized, not painted or buff/natural finish. These Tokico parts are getting harder to find 

I did complete rebuild before I before I took pictures.  You can see the outside brake disc is still rubbing with no room to move.  I replaced the outer pad with an old one and tried to centre the wheel better.  I have clearance now but have not refilled master.  Going to check return hole and giver a whirl.  

Yes outer pad appears to be all the way back. Disc looks from what i can tell off center too, might be just a photo illusion though. I have seen my share of these calipers misaligned from someone getting in a wreck. Check for wear disc marks in underside, easily noted where disc rides in caliper cutout cavity. Unfortunately these, if the case, can't be straightened. Like a brake/clutch lever, will just snap-off or fracture. Have a look and report back.