xj master cylinder nightmare!!!

i rebuilt my mc and bled the brakes for 3 days... no bubbles, but no pressure either... took it out for a ride, stopped great and then..... nothing. all signs would point to air in the lines, but there cant be... questions... all IF questions... If the cap had a leak, would it do this? IF the mc had some scores in it, would it do this? or could it be the caliper or lines? there are no leaks anywhere in the system.... My lest step before replacing rebuilt mc was to feed fluid backwards... from the bleeder to mc. im done trying this... if i dont get this fixed, im riding without brakes... i dont care anymore.... PLEASE HELP OH WISE ONES!

 

3 Days could be the new Worlds Record!

Take off the MC Cover.
Use a Syringe to remove half the Brake Fluid.
Level the MC and work the Brake Lever.

IF, ... Brake Fluid "Shoots-up" like Old Faithful, ... the MC is not developing Hydraulic Pressure and Pumping-out Brake Fluid.

It only takes a speck of Foreign Matter on the Cylinder or a Pitted Bore to spoil the Seals developing PRESSURE.

Unless the MAIN Seal is Fluid Tight, ... the MC won't develop Pressure.

 

i love you.... lol... like really do... only answer ive gotten in 2 months that makes any sense... with the cap off, and the lever pumped... it shoots out of the small hole like the bleeder screw should be doing while open... so while everyone says boreing is not an option... where do i get a new mc without paying $240? i saw one on mikesxs for like 80, but not sure if they are the same as the 80 xj650 maxim

 

This trick is probably ...
Before you were born "Old School"

REAL ... Old School!

Take a round fiberglass rod, .... like the ones they sell to mark driveways in winter.
Cut yourself 8-Inches.
Duct Tape the edge of a sheet of 800 Wet-O-Dry to the Rod.
Roll the Rod and take-up the Sheet.
Tape another Sheet on ... UNDER the 1st one.
Keep adding sheets until the Roll is big enough to be "Stuffed" into the Bore.
It needs to be tight.
Chuck the Rod in your Drill.
"Hone" the Bore with the 800 dry.
Don't hold it in one place, ... move the Roll in and out.
Add another layer if the Roll gets loose.
Hone the Bore clean. Remove matter and tiny Pits.
Once the Bore is refinished, ... WET the 800 with WD-40 and do a rapid In-Out maneuver applying a New Finish to the Bore.
Clean-out with BrakeKleen.

Assemble and Test!

 

See Section J

http://www.xjbikes.com/Forums/viewtopic ... rt=30.html

Oh and by the way

Pls post this on Youtube! :lol:

 

Did you use new crush washers and bolts or re-use what you had?

 

i reused what i had... i rebuilt the mc and i know i did it right... but after being told even a small score will cause it not to work, i went to my other maxim... took off the mc at the banjo, and squeezed the lever... pressure like a you know what.... this one doesnt have that pressure... just a little bit... so i know its the mc. it had a small score in it but didnt think anything of it... cleaning this mc for my other maxim today and bought a new one for this one. i cant believe how much this site is so wonderful. i just hope one day that i can be as helpful to someone else

 

A rule of thumb is to never re-use the crush washers. Once used they have done their job by being "Crushed".
On older systems it's usually recommended to replace the "Bango bolts" as this is an area where "Crud" can accumulate.
They are cheap to purchase and can save some headaches when rebuilding a system.
This may not be your problem, just sayin'.

 

In a pinch, you can heat the old crush washers till they glow red, then let them slowly cool off. This will anneal the washers enough so they will regain some pliability.

 

What's the best way to clean a banjo bolt?

 

Banjo dip!
No, really. Just a good soak in brake cleaner, then compressed air or pipe cleaner and it should be clean.

 

If the inner passages of the banjo bolts are full of crud that brake cleaner won't get, find a drill bit that somewhat snugly fits inside the passages and give it a few twirls.. Then rinse the bolt out with some more brake cleaner. You can use the household scouring pads to buff the mating surfaces of the bolts so they're nice and smooth.