Custom Rear Brake Reservoir '78 650S

[isaiah935]

Hey everyone, so during the process of my little chopper build I searched everywhere for some sort of rear brake reservoir that was small enough to look good on the back of my hard tail but i couldn't find anything that i really like. Long story short I designed a reservoir myself and actually had it 3D printed. Being as though your regular glycol based brake fluid is rough on a lot of plastics I opted to use a silicon based DOT5 brake fluid because it was a 3Dprinted part. It's been on the bike for three months now with no issues. I was just wondering what you guys though about it, if you think it's safe, not safe, or gonna kill me. Also would anyone be interested in this type of thing for your builds? I made it to fit a 78 xs650s but i don't know what other years and models that particular master cylinder was used. As always you guys are the best and happy building!

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• isaiah935
• Aug 8, 2016

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• isaiah935
• Aug 8, 2016

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• isaiah935
• Aug 8, 2016

PS: I wouldn't mind if y'all just pretended all the welds looked good

 

[fredintoon]

Hi Isaiah and welcome,
I just looked at your bike photos. Nice looking minimalist styling BUT
No front fender lets the forks go all wobbly, think about adding a fork brace.
If the pipes are as sawn off as short as they look to be it'll be a swine to get the engine running nice.
Think about extending the pipes back and fitting some kinda mufflers for backpressure.
The conical pleated carb pods will upset the carbs air intake, Unipods are way better.
Do all that and it should run as nice as it looks.
But back to your printed brake reservoir. AFAIK all XS650 rear brake M/Cs are the same.
It sure looks better than the plumbing elbow and transparent plastic hose that some others are using.
But DOT5 at the rear and DOT3/4 at the front? I'm sure you know that the two don't mix.
I'd have given a test strip of your printer plastic a 3-month soak test in DOT3/4 to hopefully avoid
running two incompatible fluids in one bike's brakes.
And what bad welds? You should see mine. "Length will replace Strength" I reckon. Which is why
I limit my welding to items where you can run a 4" weld instead of 1" and leave tubular welds to others.

 

[isaiah935]

@fredintoon thank you very much for the advice! You've definitely given me a lot to think about. I has definitely given me some tuning troubles too, i have can opener baffles in the pipes to try and get a little back pressure but i have read some places that that can be worse sometimes. i have been keeping an eye out for another exhaust system.
As far as the brake things go, yes i am running dot 5 in the back and 3 in the front. I haven't messed up and mixed them... yet. The first iteration of my little reservoir didn't work out so after taking it off i put it in a cup full of dot 3 about two or three months ago. So far it seems to be structurally sound still but i suppose it could only be a matter of time.
Again, thank you for the advice and time it took to reply.

 

[fredintoon]

Hi Isaiah,
Try our classifieds for longer pipes, sometimes you can find real bargains if the shipping costs don't kill the deal. Usually not too bad within the USA
but a Canadian buying a part from the USA will pay as much for shipping and duties as he did for the part and that's without considering our 70cent Canadian Dollar.
And you have your prototype printed reservoir set up as a soak test for DOT3 and it's still OK after 2 or 3 months? That's great!
But what are you using on the brake M/C in it's place?
BTW, your photos show your bike with the stock front disk and M/C. OK, that brake works not too bad but it can be greatly improved.
The basic design flaw is that the M/C piston is too large to operate a single caliper so the brake pull feels all wooden.
What I did was add a leftside disk and caliper, switch the fabric brake hoses for stainless and drill the disks full of holes.
What I should have done instead of adding the leftside disk and caliper is to fit an 11mm piston diameter aftermarket M/C.
Same sweet brake feel and half the unsprung weight.

 

[isaiah935]

I had a slightly different design printed that worked a lot better so i am just using that and have no use for the old one. I'll definitely give the classifieds a browse. I have noticed that the front brake does feel different than anything else i have, still grabs better than the old ironhead though! The first few times through a new bike there's still so much you don't know and it's awesome to talk to someone that knows their stuff.