XS850 - Monoshock & USD Fork (pics pg 13)

[treitz]

Re: XS850 - Monoshock & USD Fork

Alright, so I gave the parts all a good cleaning, checked the bore, and put it all back together. Same result. The bore and seals all looked good, so I'm a little baffled. It's pulling about 80% air and 20% fluid. See photo for reference.

Decision... buy replacement parts and trust that the bore is actually OK, or buy the entire replacement on eBay for about the same price. Risk is that one is messed up too.

 

[Tune-A-Fish]

Re: XS850 - Monoshock & USD Fork

Alright, so I gave the parts all a good cleaning, checked the bore, and put it all back together. Same result. The bore and seals all looked good, so I'm a little baffled. It's pulling about 80% air and 20% fluid. See photo for reference.

Decision... buy replacement parts and trust that the bore is actually OK, or buy the entire replacement on eBay for about the same price. Risk is that one is messed up too.

Before buying parts (I think buy the clip on with master on eBay) you might eliminate the caliper having an issue... being that you have the neato sucker tool and you are sure your not pulling air from the bleeder threads, can you cap the inlet or just stick the line in a bottle of fluid and try pulling fluid through the caliper eliminating the master? One or the other you pull air from the caliper somewhere or you pull fluid with no air from the submerged line ??? ;D

 

[treitz]

Re: XS850 - Monoshock & USD Fork

Before buying parts (I think buy the clip on with master on eBay) you might eliminate the caliper having an issue... being that you have the neato sucker tool and you are sure your not pulling air from the bleeder threads, can you cap the inlet or just stick the line in a bottle of fluid and try pulling fluid through the caliper eliminating the master? One or the other you pull air from the caliper somewhere or you pull fluid with no air from the submerged line ??? ;D

Great point. Process of elimination is always good. I'll give that a shot before ordering anything.

On a positive note... I got the back brake bled! 1/3 of the way there...

 

[xb33bsa]

Re: XS850 - Monoshock & USD Fork

have you tried just bleeding the master then instead of a line on it just plug it, a stack of washers, whatever ,see if it holds after being bled on its own

 

[treitz]

Re: XS850 - Monoshock & USD Fork

have you tried just bleeding the master then instead of a line on it just plug it, a stack of washers, whatever ,see if it holds after being bled on its own

Plugging it to see if there is a leak in the plunger/bore?

 

[Tune-A-Fish]

Re: XS850 - Monoshock & USD Fork

Good point XB... a stack of banjo washers on the Master instead of the line, use it as a bleeder if you want then tighten it up snug and pull the lever, if it leaks you'll find it!

 

[treitz]

Re: XS850 - Monoshock & USD Fork

Can you guys explain to me the purpose of the bleed screw on the top of the master cylinder? I am not very familiar with these modern MC's.

 

[xb33bsa]

Re: XS850 - Monoshock & USD Fork

Plugging it to see if there is a leak in the plunger/bore?

plugging it to see if it will bench bleed and come hard as a rock at the lever
and yeah if it sucks air then there is an issaue you will see as well

 

[xb33bsa]

Re: XS850 - Monoshock & USD Fork

Good point XB... a stack of banjo washers on the Master instead of the line, use it as a bleeder if you want then tighten it up snug and pull the lever, if it leaks you'll find it!

yep or what i do is part off a pieace of tube in the lathe but same

 

[focusinprogress]

Re: XS850 - Monoshock & USD Fork

hard to tell in the pic, but if you don't have grease around the bleed screw there's a good chance a portion of that air is coming through the threads.....that's why I hate those vacuum bleed tools....I actually backwards bleed mine with a medical syringe forcing fluid through the bleed screw to push the air up to the master and do so until theres no air bubbles coming into the master....then I traditionally bleed it for 2-3x and run it.

 

[treitz]

Re: XS850 - Monoshock & USD Fork

hard to tell in the pic, but if you don't have grease around the bleed screw there's a good chance a portion of that air is coming through the threads.....that's why I hate those vacuum bleed tools....I actually backwards bleed mine with a medical syringe forcing fluid through the bleed screw to push the air up to the master and do so until theres no air bubbles coming into the master....then I traditionally bleed it for 2-3x and run it.

The threads are wrapped in teflon tape, so I'm fairly confident it's not coming from the threads. I thought the tool this guy had was a syringe, but it ended up being a vacuum tool. I may see if I can find a syringe locally to give that a shot.

 

[hillsy]

Re: XS850 - Monoshock & USD Fork

That's a lot of air coming through the bleed nipple. How "open" do you have it? You should only open it until it starts to flow - probably about 1/4 turn.


Get a syringe and push fluid through the nipple and back up the line. That way you're not fighting gravity.

 

[treitz]

Re: XS850 - Monoshock & USD Fork

That's a lot of air coming through the bleed nipple. How "open" do you have it? You should only open it until it starts to flow - probably about 1/4 turn.


Get a syringe and push fluid through the nipple and back up the line. That way you're not fighting gravity.

I'll see if I can find a syringe while I'm out tonight. Maybe I opened it too far... probably over a 1/4 turn but not sure.

 

[Tifun]

Re: XS850 - Monoshock & USD Fork

I dig this bike a lot. I've recently started working on my USDMONO build again...I hate my bike though...


-Keith

 

[focusinprogress]

Re: XS850 - Monoshock & USD Fork

I've made it work using a cheap $2 syringe from walmart, but it was very small. I asked around and one of my buddie's wives works in a clinic and got me a monstrous one that works amazing for this.

 

[treitz]

Re: XS850 - Monoshock & USD Fork

Before buying parts (I think buy the clip on with master on eBay) you might eliminate the caliper having an issue... being that you have the neato sucker tool and you are sure your not pulling air from the bleeder threads, can you cap the inlet or just stick the line in a bottle of fluid and try pulling fluid through the caliper eliminating the master? One or the other you pull air from the caliper somewhere or you pull fluid with no air from the submerged line ??? ;D

Soooooo via this method, I think I have determined that it IS in fact my calipers that have the issue, not the master I dropped the line into a jar of brake fluid, put the vacuum on, and had the exact same results. Bleed screw threads are wrapped in teflon tape, so I highly doubt it's coming from there.

So, are they rebuildable, or should I just grab a replacement set? I found tested and working pairs on eBay for around $60.

 

[Tune-A-Fish]

Re: XS850 - Monoshock & USD Fork

Tough call, kits are not that cheap, but would be fresh clampers... in this situation you don't know for sure why, so I would go with the eBay parts and have the spares to monkey with and maybe sell off for a few dollars refund.

 

[Tune-A-Fish]

Re: XS850 - Monoshock & USD Fork

I would fully eliminate the Master with the XB test also cash is not free, but certainty is in this situation.

 

[treitz]

Re: XS850 - Monoshock & USD Fork

Yeah good call. I have the washers, so I might as well run that test too.

 

[1fasgsxr]

Re: XS850 - Monoshock & USD Fork

The calipers are from a 636 ? Take em apart...they are simple..possibly just a clogged passage