I'm in the market for lids for the front and rear brake fluid reservoirs. Want experiment with making a "pump through" fluid bleeder. Its a 1990 K100LT, ex-police, with ABS. If any of the lads going to Guyra in November have these lying around in their sheds, and surplus to requirements, will be greatly appreciated!

See you in a few weeks.

Rickmeister.

Hey Rick, 

The front lid may cause a bit of grief.  The problem with it is is a rectangular shape and not round like the rear and earlier R series master reservoirs.  Whereas most of the non-motorcycles ones are circular and give a good seal, the K front is a different shape. 

The power bleeder that I used suggested that you pressurise the reservoir to 10 psi before adding fluid and bleeding the system.  Due to the leaks through the the three bolt holes, rectangular seal and small vent (?) lip on the underside of the lid I was unable to get more than about 1 psi.  I cut rubber seals to size, used sealants on the holes, included allowing it to cure first and I leak checked it different ways and was not able to stop the leaks.  I had a spare master cyclinder to practice on so as not to spill brake fluid all over the paint work. 

I eventually gave up in frustration.   Perhaps someone else may have some better ideas. 

Cheers, Dave.

Ah you too Dave I had exactly the same problem when I tried so I made a Vacuum bleeder that eventually got the air out from that dumb crossover tube.

Rickmeister, can't help with the lids but I used a contraption made by Victa to extract oil out of lawn mowers
by suction. It worked a treat on my rear bleeder. I don't have ABS so maybe it's all different but it kept up a nice suck er vacuum in the line. Need to attach a smaller diameter hose bit on the end of the sucker to attach to the nipple. I gotta go now, blood pressures rising.

Thanks for that, lads. My understanding of a hydraulic brake system is:
When the brake lever is in its home position, there is a passage between the "load" side of the operating piston and the fluid reservoir chamber. As the lever is pulled, that passage is covered and sealed by the rubber "piston", creating a closed hydraulic system.

If this is somewhat correct, I thought that I might be able to "force" the fluid through the system, via the reservoir, interconnecting passage and eventually out through the bleed nipple at the caliper end.

So, with the lids, I was thinking of putting some sort of spiggot in the top and maybe use a vet's syringe to force the fluid through. But, I can understand Dave's grief with sealing the  rectangular lid on the front brake reservoir.

As I don't have any spare ones to muck around with, I might abandon the project.

Cheers, Rickmeister.

I recall someone here or it may have been the Motobrick site where they used the syringe to force the fluid through from the caliper to the master cylinder, which makes sense as the bubbles will always go up so you wont be fighting that and it seems to be a large part of the difficulty of getting the front brakes air free.
One thing we used to do with the troublesome Hondas was after we gave up we would tie the lever to the handlebar as tight as possible and in the morning when you release it some air would escape from the master cylinder.

Rickmeister, if you go ahead with your idea, it may be simpler to just fit a tyre valve to the lid (just one hole required) and pressurize the system with a tyre pump.

Just a thought.

Paul.

Ulrich,
If you want to try and pressure feed the brake fluid from the bleed nipple upwards, (as Rick suggested) here's something I made today that should do the job.

Basically, it's a jar with a tight fitting lid, two tyre valves, some fibre washers and some tubing. I made it deliberately using bits that don't need any machining, so it could be made by anyone.

One tyre valve, complete with it's Schrader valve, is fitted to the lid.
The other valve has the Schrader valve removed, and the base sawn off, so we are left with a threaded tube that is fitted to the jar lid with half the thread inside and the other half protruding through the top. A length of tube is then fitted on the thread to go inside the jar.

In use, a tube is fed from the jar to the bleed nipple and the jar is pressurised with a tyre pump.
   



Two words of caution, don't put too much pressure in the jar, a couple of strokes from a bicycle pump should be adequate, you don't want a fountain from the reservoir!
And be careful that the reservoir doesn't overflow, spreading brake fluid everywhere.

This idea just came about from your post, so I've not tested it, but the jar does hold a few PSI pressure so I think it would work.

So, there it is if you want to try it.
Cheers,
Paul.