XS2 Front brake performance question.

[Yamadabadoo]

Hi all,

I’ve just rebuilt an XS2, came from North Dakota. All parts of the bike work very well after recommissioning but full front brake (all parts from Master cylinder to caliper are new) is quite lacklustre. Takes a while to slow the bike down, takes a lot of pressure to engage and feels quite spongy, even after bleeding and topping up to required level. Any ideas or is this brake just like that? Any help greatly appreciated.

 

[GLJ]

Front brake should work very well. Sounds like there is still air in the system.
Where did you get the master cylinder?

 

[GLJ]

Also what does the disc look like and what are you using for brake pads?

 

[arcticXS]

If anything, the stock master cylinder, or repop of the stock one is most likely too big. The caliper used on XS2, TX A/B and XS650C is the same as used on the RD350, various TZ250/350/500/750 models, and is pretty good IMHO. With a suitable size master cylinder, good braided hoses, and good pass, you should have a decent front brake.
On my RD350A, I use a 13 mm Brembo master cylinder. Any conventional master cylinder between 12 and 14 mm should improve the brake significantly. I believe the stock RD mc was 5/8" almost 16 mm.....

 

[Yamadabadoo]

Yeah, I thought it felt like air, I just have no frame of reference as this is my first XS650 (won’t be my last though, I love it so very much). I’ve got a choice of discs, the one that’s installed is a standard XS2 item which has been drilled professionally and the other is the stock disc, 100% original. The master cylinder is a repro bought from Yambits here in the UK. Here’s the link. https://yambits.co.uk/xs2-brake-master-cylinder-p-93898.html All other parts have been sourced from here too. Pads are just the ones that come with the new caliper. If anyone has recommendations on pads that would be great too.

 

[GLJ]

I've used the same MC with good results. Braided line are better than stock rubber ones but rubber lines will work ok. I would suggest going back and bleed it again.
Could help if you post some pics of the disc and pads. General pics of the bike would also be good.

 

[Wingedwheel]

I kept having an issue with air somewhere in the line. I left a clamp on the brake lever overnight and the problem seems to have been corrected.

 

[gggGary]

There's a lot of one year only parts in that brake set up are they all there, in the correct order?

 

[Yamadabadoo]

Thanks for the wealth of info folks. As soon as I’ve got some time I’ll go out and take some photos as well as detail shots of the braking system. Yeah I’m pretty sure the system is complete. There’s nothing in those photos that jumps out as “never seen that before”. So, for a little background, I already rebuilt this bike once before last year and unfortunately was involved in an accident on it (not my fault). The bike was recovered and front forks, front wheel and mudguard all replaced. No major damage other than that luckily, I’ve since had it down to bare frame to have it checked, professionally for any frame damage. At the time, it had the new MC but original lines, caliper and disc. I’ve installed new swing arm pivot tube, bolt and brass bushes from Heiden Tuning, original stuff was all stuck fast on disassembly. Thought it wise to install the new caliper, pads, lines and a drilled disc as a precaution against future incidents. I’ve completed extensive work on it, it was a non runner when I got it. More pics to follow. The only thing I’m unsure about is the rubber between the hub and disc. At the moment there is nothing there, does anyone have photos of what’s supposed to go there/ any sources for replacement? I’ll try bleeding again and see how I go (already completed the bleeding process multiple times). I’ll try a clamp on the lever overnight and see if that helps. Hopefully it is just air in the caliper, that’s looking more likely than anything else right?

Edit: just found the thread about the dampers. I’ll make some, so all good on that front.

 

[gggGary]

Missing pads will just make for noticeable click/clunk on brake application.

I might remove the caliper and check that BOTH pistons are moving freely.
One stuck piston could create the symptoms you describe.

 

[JJames]

Are you bleeding the system top down or bottom up? I've had good luck using a large syringe(20 ml. Min.) And a short length of tubing that will fit the syringe and the bleeder nipple. You can then push fluid up through the caliper and lines and out at the MC. Gentle tapping or shaking will dislodge air bubbles and they will naturally float upwards . Be careful not to overflow the MC or spray fluid on painted parts.

 

[Yamadabadoo]

That’s a good idea, I’ll give that a try when I get home. I’ve been bleeding from the top down up until now. I did try it again with the bike canted over to the right and therefore pointing the bleed nipple up, (MC cap on) arguably making it the highest point on the caliper and got some air, then solid fluid again. Lever seemed to harden up a lot sooner after this but I was unable to take it out and test it before work this morning. Will report back later this evening.

 

[dave_a]

My '74 TX brake left something to be desired. New master and caliper/pads from Mikes. Although the system had new fluid, the lines and manifold under the bottom clamp were filthy with rust & mung.
Complete disassembly, thorough cleaning and flushing(alcohol after parts cleaner), reaming. It was really contaminated. Slapping new parts was only half the problem.
80grit on the discs & pads. 4-6 repeated high speed to almost stopped, bedded the pads. Much improved. Not modern dual disc Brembo one finger good, but good enough. You have to squeeze it like you mean it tho'.

 

[Yamadabadoo]

Hi all, quick update, brake feels significantly better after bleeding canted over to the right, stops with much more authority now. Once I have time at the weekend I’m going to strip it down, make some dampers and put it all back together. I’ve included some photos best I can at the moment. I’ll also grab some more brake fluid and a syringe to finish bleeding and make sure I have no more bubbles as well as some 80 grit on the pads and discs to bed them in. As you can hopefully see from the photos, the disc is a standard unit which has been drilled. All other parts appear to be present and accounted for. Out of curiosity, the photo where the banjo bolt is visible, have I installed the washers incorrectly? Should it be one on either side of the brake line? Just spotted that and can’t remember if it’s my mistake or if it was always like that.

 

[GLJ]

have I installed the washers incorrectly? Should it be one on either side of the brake line?

One on each side.

You also have the brake line run incorrectly. It should run behind the lower triple tree. Then there should be 2 holders that it runs thru.

The bracket you are currently using goes on the other side. It's for the speedo cable.

 

[Yamadabadoo]

Excellent, thank you so much, the way I’ve put it together is the way it was when I got it, I’ve never been able to see these details on an all original XS2. The brackets for the brake lines have never been there in my ownership. The original lines were held in place with zip ties. I’ll make these adjustments ASAP. Incidentally, do you have a link for the brake line? What brand is it?

 

[GLJ]

The brake line is Hel. Not cheap but very good quality.
https://www.helperformance.com/yama...ement-brake-lines-hel-stainless-steel-braided

 

[GLJ]

For the rubber bit I use strapping. Post #51.
https://www.xs650.com/threads/sorry-yamaha-but-that-was-dumb.16441/page-3#post-767812

 

[650Skull]

If you look at the Yamaha bulliton gggGary posted in post #8 it shows Yamaha discontinued the 2 pads and replaced with a rubber ring.

 

[Mailman]

If you look at the Yamaha bulliton gggGary posted in post #8 it shows Yamaha discontinued the 2 pads and replaced with a rubber ring.

These photos show, both, the factory rubber pads and the o-ring , for some reason my XS2 had both and that’s the way I left it.