Front brake caliper question

[MotoFo]

I have two KDX200s - 1995 and 2003. The 2003 is experiencing a very touchy front brake to the point where it locks up easily. I'm thinking the caliper needs to be rebuilt. I also looked on eBay and new, no-name calipers are going for about $50. Has anyone tried one? I am skeptical. The 1995 front brake doesn't seem quite strong enough - pull in the lever pretty far to get full power though it has the correct amount of free play. Perhaps a steel-braided brake line is in order.

[KDXGarage]

They are 23 and 31 years old since manufacture date of the parts. I would try a rebuild of OEM before buying a no-name.

[billie_morini]

Touchy hydraulic brake? Makes me think the master cylinder plunger or slave cylinder piston are not completely retracting. I would:
1) Clean the rubber seals around the piston at the slave (caliper [tooth brush & gentle compressed air)]
2) Re-align entire front end (by Kawasaki shop book method or Suzuki DRZ wheel spin method)
3) Clean the rubber seal at master cylinder, looking especially for crunchy bits (tooth brush and gentle compressed air)
4) Bleed the brake like (I like vacuum pump followed by overnight zip tie on hand lever)

If the steps above don't fix it, then I would rebuild the master master cylinder and caliper. Important to use compressed air in small diameter channels in the slave (caliper).

I did all the above that was applicable to the rear brake on my 1988 K75S. The rebuilt master cylinder leaked. Original BMW/Brembo rear brake master cylinders are not available. I bought a couple of China made, closely examined and compared them with each other, shortened the external activation arm, and installed it. I was uneasy using China made. However, it's been working well for 2 years.

[MotoFo]

Thanks for the info!

[kdxdazz]

As stated a full rebuild on your caliper and master cylinder is best but I know that's easier said than done if you have never rebuilt them before, sometimes no parts are needed to be bought, everything just needs to be stripped down and cleaned thoroughly, pay particular attention to cleaning out the corrosion from underneath the seals and use silicone grease in the dust seal, must be silicone as regular grease swells the seals,buff any rust or dirt off the caliper pins, use 800.grit sandpaper to lightly buff the pistons, remove the bleed nipple, wire brush any rust away, clean, wrap with teflon tape and a smear of grease, this makes fir easier one man bleeding using the reverse bleeding method

For the master cylinder completely strip it down and wash with soapy water and dry with compressed air, I like to wrap a wooden chopstick with 800 grit sandpaper and lightly hone the bore shining a torch to check for scratches, use the torch again to check both the bleed hole and fill hole are clean from debris

I used to hate brake rebuilds now I love them

[MotoFo]

I ended up having to replace a caliper piston as part of the rubber was chewed up. The brake is working good now. However, I did notice that the outer part of the front rotor has play. This is the part outside of the circular rings. Is this normal or does the rotor need to be replaced? Thanks,

[Chuck78]

These are a floating rotor design. They are supposed to have a very slight bit of movement, but if you are complaining about it, it is probably beyond the acceptable range of movement by a wide margin and could be replaced. It will continue to work as is for a while though.
I thought I had worn out fork bushings in my bike from the first two rides of the season, but it turns out my brake caliper is just worn where it slides on the sliding pins on the caliper bracket... This I haven't experienced yet but I do brake pretty darn hard at times and the bike is almost 30 years old, after all...

[KDXGarage]

It's a floating rotor, should be normal to wiggle some or "float".