Brake caliper, restorable?

Folks,
I took my newly aquirred XJ750 for a short test ride, until the right front caliper froze up. Can it be repaired or restored? Must it be replaced? ($300!)
Let me know, thanks.
Bill

 

Shouldn't be too much of a problem, and you can get the rebuild kit for the caliper and the master cylinder from Chacal quickly, and at very reasonable prices.

 

A lot of times it's not the caliper itself but the "sliding" mount it's on. Both my 550 Secas had an apparently "sticking caliper" when I got them, both were NOT the caliper itself, just the mounting block and "sliding pin" not allowing the caliper to move freely laterally in its 'holding block." Disassembly, cleaning and careful lube upon reassembly and bled the brakes, and they're both fine. I bought a caliper piston and rebuild kit, and don't need them (yet.)

 

Guys, I wanted to post a pic of the caliper piston, showing lots of dammage around the upper rim, extending 1/4" down the pollished surface. It wouldn't take the image. That said, take my word for it.
It looks like some mope put a pipe wrench on the piston. I'm sure it must be replaced.
Anybody know a source for a couple good caliper pistons?
Bill

 

If you email me the pic I'll post it, either on here, or on a webserver and link to it.
my first name: daniel
my last name: turner
with a '.' between them @ okstate.edu

 

If it's ONLY a 1/4-Inch you should be OK.
That outer part never gets close enough to the Seals to need to be absolutely beautiful.

But, if it has Tool grabbing marks past the "Outside Shadow" of exposure to the elements. You might need a replacement Piston.

Take the Piston and wrap a few turns of Masking Tape right at the "Shadow" Line.
Take some 800 Finishing Paper and hand-sand the burrs and gouges down until they are smooth.

Throw it together and see if the Caliper is OK or it leaks.
You have a good shot at it being just fine if the Tool Marks are within the "Outside Shadow" that doesn't ever get below the Hydraulic Seals.

 

Caliper pistons, in stock, and they even come with replacement seals:

Disc Brake Piston:


db2) OEM and aftermarket DISC BRAKE PISTON, brand new pistons replace damaged or scored originals perfectly. If a piston needs replacing, always be sure to check the condition and roundness of the caliper bore, and re-finish or replace the caliper if necessary.


HCP753 OEM front disc brake CALIPER PISTON, includes one brand new piston and a piston fluid seal and a caliper dust seal. One kit does one caliper. Fits all XJ550 models, all XJ750 Seca models, and XJ1100 front calipers. Each:
$ 64.00

HCP753SET2 OEM front disc brake CALIPER PISTONS, includes two brand new pistons, piston fluid seals and dust seals. Fits all XJ550 models, all XJ750 Seca models, and XJ1100 front calipers. Pair:
$ 125.00



HCP1703 Aftermarket disc brake CALIPER PISTON, includes one brand new piston and a piston fluid seal and a caliper dust seal. One kit does one caliper. Fits all XJ550 models, all XJ750 Seca models, and XJ1100 front calipers. Each:
$ 49.00

HCP1703SET2 Aftermarket disc brake CALIPER PISTONS, includes two brand new pistons, piston fluid seals and dust seals. Fits all XJ550 models, all XJ750 Seca models, and XJ1100 front calipers. Pair:
$ 95.00



HCP1936 OEM front disc brake CALIPER PISTON, includes one brand new piston and a piston fluid seal and a caliper dust seal. One kit does one caliper. Fits all XJ650 Turbo models and all XJ750 Maxim and Midnight Maxim front calipers. Each:
$ 52.00

HCP1936SET2 OEM front disc brake CALIPER PISTONS, includes two brand new pistons, piston fluid seals and dust seals. One kit does one caliper. Fits all XJ650 Turbo models and all XJ750 Maxim and Midnight Maxim front calipers. Pair:
$ 99.00

 

Before I read this, I put the piston in a vice, and carefully filed the high spots down, and sanded. I put it back together, and bled the air bubbles out. Seems fine, but I won't be able to road test the bike until I stop the fuel bowls from overflowing. But for that I have some guidelines.
Thanks!

 

I'm glad you're making progress, proto, it takes some perseverance to get everything just right.
You taking it "One step at a time" is definitely the way to go.

What do you think is causing the Fuel Bowls to overflow.
Stuck Floats?
Float Height?
Old Float Valve Seats and Pins that ought to be replaced?

 

Carb overflow?

You asked me at the right time. To start at the begining, gas driping out the air box, one drip a sec. as the bike sits on side stand with engine off, petcock on prime. It eventualy stops with petcock set to ON. I know why.
After testing this leak, it seems carb. #1 is leaking bad, and #2 semi bad, #3 & 4 OK. All drain plug screw heads are stripped. (I read how to replace them.)
Took carbs out, opened float bowls and checked the difference in float level settings between bad #1 and good #4. #1 level was set for a lower gas level than #4, I didn't expect that. :?
The valve seats and pins look good, and clean.
Could the float for the bad #1 carb be less buoyant?
Any suggestions for my next move?

 

Back when they were making Floats out of Brass and soldering them together; there was always the likelihood that a Float could "Spring a leak" and fill-up rather than float.

With the advent of the Solid Material Floats; that situation ended.

If you leave the Petcock on PRIME; you risk having Fuel pass into the System and a Fuel Tank with a large quantity of Fuel can leak-by a Float Valve that isn't firmly seated.
. . . . . . . . . . . . . . .
Set your Float Heights to all be within specs.
Set the Petcock to ON -- Not PRIME
If the problem persists; you Test for leak-by at the Petcock.
If the problem is solved ... move-on to something else.