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Help, I have a 98 k1200rs. The flexible brake hose coming off the master cylinder for my front brakes failed. I replaced it with one from the dealer and now im trying to bleed the brakes without any success. After opening the bleeders on either the abs unit or the front wheel calipers, I cannot get fluid to flow thru the lines. When I pull on the front brake lever, it just stops. I am able to get fluid out of the rear brake caliper without any problem. What am I doing wrong ?
 

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It can take a long time pushing fluid through a new hose,or even prime the master cylinder if empty, doing that by hand on the old GS meant pumping 3-400 times. :( Not too good on master cylinders slamming the piston inside the cylinder when pumping, my method, same as recommended for most cars (and little known...) is to put something on the handgrip to avoid that.(2x4 under the pedal for most cars)

What worked best for me was to rig some suction on the line, rubber hose and large syringue,and with the lever depressed fill up the hose/master cylinder by sucking on it keeping the reservoir full all along.You may have to repeat that a few times til the fluid comes out. Then remove the "rig" and trying not to loose/spill much fluid quickly reattach the hose. Then proceed with regular bleeding.

There is also them vacuum extractors/brake bleeders, I just bought one for similar situations, cheap at Harbor Freight, but haven't tried it yet. With those you can suck right at the bleeder, syringues are too wimpy for that, but note here that Vacuum Bleeding is not recommended by BMW on the later ABS systems, I think yours is OK but check the book first.

Once you have done all that, you may want to attach the lever to the handgrip with a Zapstrap and leave it for a day or so, then inspect for leaks. It took that long for one to show up on my bike after a full line replacement. Much easier and safer dealing with that in the shop than "on the road". That is also the trick to remove all air that could still be trapped inside the master cylinder, they are notorious for that as in.....hard getting all the air out of them. With the lever attached the air bubbles will rise and eventually come out through the reservoir.For that last part the reservoir has to be at the highest possible position, usually achieved by turning the handlebars, but sometimes the handgrip also has to be turned depending at what angle it is installed originally.

Good Luck!
 

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Manually bleed the master cylinder at the banjo connector, then work down to the calipers. By 'manual' I mean put something under the banjo to collect fluid and stop it dropping on the painted fender (!!). Pull lever, release banjo, clamp banjo, release lever and repeat until fluid is coming out. Once I had to take the handlebar off, hold it at 45 degrees and manual bleed to get the air bubble out of the master cylinder.

It will come good - eventually.

PS I use a vacuum bleeder on my '97 (ABSII no servo) but it only works well if you remove the bleed nipple and wrap a couple of turns of teflon tape around the threads.



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