xs weak front brakes but good flow?

[klrconcours]

Can it be, despite pumping a full pint through both bleeders with no sign of air I still have air in the line Up high? I love this 81 XS too much to total it and me! Lots of flow when bleeding, just have about 40% stopping power. Good pads, clean rotors...The bike was resurrected from 6 years storage. I did a thorough caliper clean and check tho.

[DGXSER]

Did you clean and check the master cylinder? They get plenty dirty up inside there as well.

[natemoen]

I had the same problem and I let it sit and the next day oddly I had pressure. Same with the back. So try letting it sit for a day or so and then go back and give it a squeeze and see what its like.

[DGXSER]

There is an "old" trick that Prom explained once upon a time. He learned it form some old guys, cause he it to your for all that.

If you think it is air stuck, then take a bungee cord or the like and tie the brake lever squeezed in about 2/3 of a pull or so. Turn the handlebars so the reservior is the highpoint of the system. Now let it sit like that overnight. Try the brakes in the morning. It has made a difference on mine more than once.

[TopCatGr58]

Hey KLR,

Yep, due to the position of the MC vs. the very low calipers, air can get trapped in the junctions and such. The handlebar lever squeeze trick is to get the piston passed the spooge hole, and so any residual air near the MC will eventually bleed/float up back into the reservoir.

IF you don't like waiting, then take the calipers OFF the forks, wedge a piece of solid wood or something same or thicker than the rotors into the pad spaces, and position them at or above the height of the MC, and then with a HELPER, bleed them again, and you may finally see the air flow out of the bleeder valve. Tapping on the MC and hoses and junctions may also help loosen the bubbles and get them flowing down/up the line!? YMMV

T.C.

[klrconcours]

THANKS! That 2/3 pull and bubbles away makes great sense! Gonna run down to the garage and get it set up! BTW there is pressure, just a firm squeezy and poor stoppy.

[TopCatGr58]

Okay, did you do a rebuild of the calipers, or are you just doing a bleed??

The old calipers can get corroded, gummed up, the piston can almost get frozen, and so you can get pressure, but it doesn't actually MOVE to compress/squeeze the rotors, and so poor braking!?

Also, the special pads look funky...slanted, that's OEM design! Did you take the calipers off and inspect the pads for glazing, fluid contamination, etc.!?

The calipers can often be rebuilt WITHOUT replacing the square shaped O-ring, just cleaning it out, scraping the corrosion out from the groove the O-ring sits in, etc., and then reassembled with brake fluid, and the piston will then be more free to move under the brake lever pressure! JAT.

T.C.

[jmnjrpa]

Ss

Stainless Steel brake lines. If you find no air and don't have them yet you will not believe the difference! I think the old rubber lines tend to expand way too much. JAT

[79XS11F]

I have had this issue as well and got the air out by removing the calipers from the forks and bleeding them with only a thin board between the pucks to keep the piston from being dislodged from the caliper. Once the calipers are real full of fluid from bleeding I use a large C clamp to push the pistons back all the way into their bores. this forces the fluid up the lines and flushes air out through the mc. Just don't over flow the mc. I used a syringe to remove fluid as it was returned to the mc.
Rob

[petejw]

u could try bleeding the master cylinder,
wrap a rag around the banjo nut so not to spray
brake fluid every where, crack the bango nut at the mc
and slowly depress the lever see if any air comes out.
also dont forget to check the levers free play, this can
also make a big difference.

[klrconcours]

Well, what I tried (5 posts up, the bungie and over night trick) didn't do it. On to try a couple of these other tips posted. Thanks. We'll see. Oh, and yes I took the calipers appart and put them back together now clean as new.

[DGXSER]

I'll ask only because it is so important and you did not specifically say it, did you pull out the rubber o-ring type seal in the caliper and get all the schtuff down in behind there out? Ddi you pull the master cylinder apart and clean everything in there?

[klrconcours]

Calipers yes. Totally like new. Master, Partially. Gonna take the whole enchilada appart today. I guess I was being lazy since it pumps copious fluid We'll see.

[klrconcours]

Master clean as new now. All rubber great shape too. Same problem. Humph! Thanks tho!

[81xsproject]

Are you both calipers at the same time? Switch back and forth between calipers. I have had luck removing the master from the bars and pumping fluid through with it in various position (but keep fluid over the intake holes or you'll just push more air in).