bleeding rear brakes

Mine has a lock nut as well.
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I tried the mighty vac but it seems like it doesn't have enough suction to pull the fluid through, maybe once I adjust the push rod it will work better, maybe the push rod is blocking the fluid coming from the resouvour. I noticed that the second picture of the other push rod no threads are showing, looks like mine might be way out of adjustment. Thanks
 
Someone needs to finish welding those MC bungs to the frame. Tack welds aren't sufficient.
 
Ok, I did everything exactly like you said.....no go! So I removed the whole master cylinder assembly from the bike, proped the resivour in a vise to hold it straight and I hand pumped the MC, nothing comes out, maybe a slight dribble, but that's it. Do I have a defective master cylinder? Thanks!
 
Another way for adjustment, and to test the shaft is going all the way into the M/C, is to remove the brake lever and reinstall, anti clockwise, say from 3o'clock to 1.30.

Also need to disconnect the caliper and have it lower than the swing-arm and get the bend out of the brake line for a continuous uphill gradient to the reservoir .........Don't forget to put a 5-6mm spacer between the caliper brake pads.

If our not still getting fluid through the bleed screw , make sure the screw is cracked enough for flow or remove it and check for a blockage. If non turn the caliper upside down, without the bleed screw and try again..........use a tray or better still an empty 4 liter oil container with the side cut out...........i use them for all my oil changes and such..........
 
Isn't there a way I can test the master cylinder off of the bike, since I have it off now, you would think if you pump the push rod in and out fluid should squirt out of the MC.
 
It should, has the piston been completely out? The brake fluid should run out of the reservoir and through the banjo fitting at a very steady drip, no pumping required.
 
It's brand new from Mikexs, when I let the master cylinder hang a little fluid comes out then stops, should the top be off the resivour? I don't understand what's wrong, when I pump it fluid should come out....right, this is really aggravating, everything is brand new, this should be working!
 
Genuine master cylinders always have that tiny second hole we originally talked about. It does easily get plugged because it's so small. Occasionally the chinese units don't have that small hole drilled completely through, worth checking that it's open. Wouldn't hurt to have the cover open or at least loose for bleeding. The passages through a master cylinder are small, trapped air can do funny things, only a little fluid is moved each stroke.
 
the hole is a passage between the MC piston bore and reservoir feed pipe there are two, a fairly large one and and very tiny one. they are quite hard to see on the rear MC.
rear MC ports.jpg
 
Ok, great, I will have to take the feed pipe off when I get home to check it out, I guess I was naive to assume this would be a bolt on and go set up......always seems to be a problem. Thanks!
 
So, what should I expect when I push the push rod in and out of the master cylinder, a fine squirt of fluid or fluid slowly flowing out? Are these after market MC prone to being bad? Is it safe to say that it's fine I just need to figure out "what's up", this is all new to me. I don't want to send it back, get another one and the same thing happens.
 
could be several things, guess I would use any vacuum to pull fluid through, first. A big syringe makes vacuum, the local farm store has them, or a knock off mighty vac from harbor freight or the local NAPA etc.. MC maker might have used some sort of assembly lube mucking things up??? Sure ain't much fun dealing with g-d brake fluid everywhere is it? I feel 4 yah, really I do.
 
Yeah, I wonder if I use the mityvac wrong I saw a video online where the guy used the long tube coming off the bleeder valve then it goes into the reservoir type bottle than a real short tube then the pump. I used a long tube between the pump and the resivour, I wonder if that affected the suction power of the pump.
 
How about back bleeding the system with a pump style oil can, would this work, do I need to have the brake pedal pressed down so fluid passes through the MC?
 
You can do that, bleeder threads tend to leak (couple wraps of teflon tape help). Don't need to press pedal, MC will pass fluid with no actuation needed, actually will ONLY pass fluid if pedal NOT pressed.
Tubing length makes no difference to vacuum pump long as tubing doesn't collapse.
 
That's what I will do, put everything back on, back bleeding the whole system, fill it with fluid, then hopefully the brakes will work properly!
 
IMHO check that the small hole in the MC is open first off. As mentioned by others doing it off the bike with a straight fluid path no air loops is the only way to get this done.
There are no shortcuts to doing brakes, only looongcuts.
 
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