Special front brake bleeding

[xs650man]

Another thought, if those are in fact original lines using that pinch tool could break the inner walls of the old lines and have bits of rubber contaminating the system.

No they are new lines

[DGXSER]

I would suggest you make sure you have all fittings good and tight.

As to air being trapped in the caliper from the reverse bleeding, it is not very likely. No harm trying it, but not likely to be the issue. Liquids seek their own level, so as you fill the caliper, from the bleed screw, and it goes up the brake line, above the level of the caliper, the brake fluid will fill all of the areas where the bleed screw is.

In fact, if you were to merely open the bleed screw on the second caliper and put a hose on it leading to a small container of brake fluid, it will fill nicely for you as you put fluid in from the other side. This will happen before fluid gets to the MC. It just is not pushing the air up as you plan to do it. But if you wait until you have fluid coming out the MC from one side to push fluid up the other, chances are you already have a decent amount of fluid in that side already.

Just to ask the stupid question, after you finish reverse bleeding, do you perform normal bleeding process? I would try that as it will get out any of the air bubbles that refused to follow the rules of physics and stuck around ad Schming suggest.

[xs650man]

I would suggest you make sure you have all fittings good and tight.

As to air being trapped in the caliper from the reverse bleeding, it is not very likely. No harm trying it, but not likely to be the issue. Liquids seek their own level, so as you fill the caliper, from the bleed screw, and it goes up the brake line, above the level of the caliper, the brake fluid will fill all of the areas where the bleed screw is.

In fact, if you were to merely open the bleed screw on the second caliper and put a hose on it leading to a small container of brake fluid, it will fill nicely for you as you put fluid in from the other side. This will happen before fluid gets to the MC. It just is not pushing the air up as you plan to do it. But if you wait until you have fluid coming out the MC from one side to push fluid up the other, chances are you already have a decent amount of fluid in that side already.

Just to ask the stupid question, after you finish reverse bleeding, do you perform normal bleeding process? I would try that as it will get out any of the air bubbles that refused to follow the rules of physics and stuck around ad Schming suggest.

Yip tried all that, finishing with normal bleeding, even unbolted the callipers to get the bleed screw lower for the reverse bleeding.

[Schming]

Maybe try this:

With bike on center stand, attach a clear hose to your bleeder, on either caliper, and run it into a clear plastic cup or such with the end submerged in brake fluid.

Use SWMBO, a heavy duty rubber band or bungee to squeeze and hold the brake lever.

While squeezing the lever, open the bleeder til lever bottoms, close bleeder, release lever, repeat til you get a solid stream of fluid, with no air bubbles, through the hose in the cup.

Make sure the MC doesn't run out of fluid and repeat process on the other caliper.

HTH

[Newbee]

Brake lines s/s install&bleed

Installed front s/s brake lines today from techna-fit the ones Ian sent in for 79F also perfect fit for my 80g the rubber grommet they put on has to be cut off it does not work used the stock one works great keeping Lines in place used the bolts &washers at come with them they take a 14mm wrench stock is 12mm I did use one 12 mm on the right side of tee fitting the 14mm was to hard to put a wrench on to tighten.Bleeding I filled MC bowl put diaphragm and cap back on squeezed brake lever quickly a number of times then held in for about 30 seconds did this about 6 times then cracked the nut at caliper some oil came out then I took the cap &diaphragm back off add a bit more fluid pulled lever again quickly and held till air bubbles came out did this again about 6 times also adding brake fluid as needed after about the third time the lever started to get hard by the sixth time it was hard held cracked bleeder a bit a little air then fluid tighten bleeder repeat other side topped off brake fluid put diaphragm and cap on.The brake lever is I feel the hardest I have felt on this bike in 34yrs.only about a 1/4'' pull on lever.I am not the fastest worker on bikes this took me 3 hours it got to cold and was snowing so I will do the rear tomorrow.I can see the rubber retainers on the rear line will not work also.

[Schming]

Yep Newbee, that's all it should take. Good job.

The rigidity you feel is the result of the SS sheathed lines.

Nice huh.

[xs650man]

Ok,some progress. Unbolted hoses from callipers, got a 10mm bolt and some copper washers and bolted the 2 calliper banjos together to form a solid connection to verify my hoses are ok, filled m/c up with fluid, bit of pumping and lever is firm. So what the hell is going on with my callipers ? Its only since I put the K&L seals in. Took the callipers apart to check the seals and it took an incredible amount of pressure to pop the pistons out, like 100 psi ! There was a small amount of crud in the seal grooves that i missed so carefully scraped that out, was like congealed brake fluid or something, I have read somewhere that some aluminium's react with brake fluid ? Will hopefully put it all back together tomorrow.

[Schming]

Brake fluid absorbs water and the mixture then corrodes the ali.

I use a small 90* pick and then a small wire wheel, carefully, on a dremel tool to clean every bit of that crap in the groove out.

Also before installing the square o-ring I coat the groove with a thin layer of silicone grease to halt corrosion.

As long as the o-rings don't leak they should be good.

[IanDMacDonald]

Omg Schming For about a week straight I had pieces of short wire finding it's way into my body and figured it was from another project I was working on. It was from that dremel wire wheel shooting it's wires out doing my calipers !

[Schming]

Omg Schming For about a week straight I had pieces of short wire finding it's way into my body and figured it was from another project I was working on. It was from that dremel wire wheel shooting it's wires out doing my calipers !

One plus for being 97 11/16 % bald is my daughter was able to find the three tiny wires stuck in my head from those wire wheels.

Even the washing machine won't get them all out of my work clothes, but it's the best way to clean gasket surfaces and a whole lot of other uses.

[John]

What has always worked for me is to remove one caliper from its mount, and the M/C from the handle bar and with the help of an assistant, hold the M/C so that the brake lever is pointing towards the ceiling. I have found that, because of the angle of the M/C, the banjo bolt is the highest point in the brake system, so air can collect there. Now using a C clamp , compress the caliper piston and any air air trapped in the banjo bolt will be expelled out through the reservior.

[xs650man]

May have found the problem, shone a torch under the right calliper while working the lever and seen a small bubble, dropped the calliper and the pads were wet, observed the piston while working the lever and sure enough, a small air leak even with the new seals. So either my pistons or calliper bores are NFG. Now thinking should I spend the money on recon callipers or a total brake upgrade,I hate the stupid Special calliper system, don't know what Yamaha were thinking when they designed it. Has anyone changed the SG to a more efficient system ? Even a whole fork upgrade maybe.

[Schming]

Might be those K&L o-rings. Were the originals shot ?

TC has a thread, in the Modification section, where he made brackets, to fit the Special's forks, to accept regular calipers.

I am changing my SF's forks to '81 MNS forks as they, and the XJ both use the regular calipers.

[xs650man]

Might be those K&L o-rings. Were the originals shot ?

TC has a thread, in the Modification section, where he made brackets, to fit the Special's forks, to accept regular calipers.

I am changing my SF's forks to '81 MNS forks as they, and the XJ both use the regular calipers.

Yes originals were shot, leaked quite bad. MNS parts are as rare as rocking horse manure over here so I was thinking of some 37mm fork legs of a totally different latter model bike ( air cooled GPZ 750 are 37mm ) those things stopped on a dime and yeah I know its a way lighter bike but its got to be way more efficient that the strange SG things.

[crazy steve]

The sealing surfaces in the special (and all the other XS) calipers is the bore in the caliper that the o-ring seats in and the outer diameter of the piston, so if the caliper is leaking around the piston one of those is bad. It's almost always the piston though; if yours has any damage like rust pitting, scratches or dings, that's a potential leak....



Here's a pic of the three piston sizes used in the various XS11 bikes; left to right they are: LH/RH/XJ front, two 'standard' front/rear and Special rear (except LH), and Special front/LH/XJ rear. All of these display damage to one degree or another, if yours look like any of these or worse, that's your problem. New replacements are available, HVC cycle is reproducing all of these in stainless steel.

If the bore in the caliper the seal fits into is damaged, that could also be the problem. Pitting, scratches or gouging from heavy-handing cleaning can cause leaks. These really need to be cleaned by hand, using a wire wheel on a dremel tool opens up the possibility of distorting the bore size which can cause leaks even with good pistons. The only fix here is another caliper body.