Fronk Brake Bleed Trick or Problem

[apogeecustom]

I have a GL and the hand bars are swept back and down. I've been having a ton of trouble getting pressure built up on the front brake. Yesterday I somehow magically got good pressure. Later in the day I was putting the brake light circuit back on the lever and I loosened the master cylinder bolts up and flipped it over so I could get the switch on with out trouble. When I fippled it back in to its correct possition I lost pressure again and I'm assuming its because I let all the fluid move away from the inlet when I flipped it over and air rushed in. So I went back to bleeding again, did the dowell rod to get the air out, bled, bled, bled, and still no pressure. So today I spent some time thinking hard about it and I observed that the cylinder has to push the fluid upward against gravity when mounted, so I loosened up the bolts again and this time slid the cylinder up the bars until it passed the hump on the bar so that the cylinder would be pushing fluid on a level plane. The pressure took immediately. I bled a couple of times in that position and put the cylinder back to its intended position and bled from there. Now I have great pressure. This is either a trick, or there is something wrong with my master cylinder. A rebuild kit is on the way just in case.

 

[Nessism]

One easy way to prime the master is to draw a vacuum on one of the caliper nipples so fluid is pulled out of the reservoir and into the pump chamber. A miti-vac works great but even a piece of tubing and using your mouth to draw the vacuum works too. Clear tubing is recommended for obvious reasons.

 

[979roadrunner]

My trick, and I use this on cars, too, is to get proper sized tubing, and drop one end into a glass jar with a little brake fluid in it (enough to submerge the end of the hose) and put the other end over the bleeder, loosen the bleeder, then pump brake slowly till I get no more bubbles.
an alternative is to run the tubing back to the master cylinder, but a bike's master is awful small for that.
The only vehicle this hasn't worked on so far (provided the master was good) is Chevys with anti lock brakes, which you have to gravity bleed unless you have a special tool.