- I just installed stainless lines on my 919 and I'm really happy with the bleed job i did on them. I think the mity-vac sucks (not in a good way) but maybe i was a bit more inexperienced when i used it. Also worth noting, i'm pretty sure i put teflon tape on my bleed screws threads. When I first used it, it just pulled in air bubbles from the threads or around the bleed screw.. it seemed way more complicated than it should be.
Having all the tubing attachments from the mity-vac was actually the most useful thing to me.
Here's what I do.
-Find a big syringe. Tractor Supply, or similar animal care places might have them. Walmart might even, i forget. It should be about 40 mL but it's not critical. The tip of mine fits nicely on to aquarium airline tubing. I'll have to measure ID when I get home.
-An attachment to go from the size tubing that fits the syringe tip, to the size that fits a bleed screw. Clear Fuel line tubing fits 1/4" i think but it's a little loose - won't leak air but it will pop off the bleed screw easily. Alternatively you can use the small airline tubing and stretch the end with a needle nose pliers so it fits over the bleed screw but it can be aggravating. Use about 3 ft of line so you can move around without pulling it off the bleed screw.
-Start by compressing the pistons into the calipers, you may need to remove fluid from the reservoir to do this.
-If there's brake fluid in the system, suck it out of the reservoir and if you want you can attach the syringe to the bleed screw and suck it out of the line. you can leave it, you'll just have more old fluid to suck out of the reservoir before the new fluid fills the line. I did this with dry lines and i'm happy with the results.
-Attach syringe and line to bleeder.
-Fill syringe with brake fluid. elevate so the fluid runs down to the bleed screw (easier with 1/4" tubing than the tiny tubing). you don't need to fill the whole line with fluid, in fact it's probably easier if you don't. So the syringe can be detached when you need to suck fluid out of the reservoir.
-You'll want to have the handlebars turned in a way that makes your reservoir higher than the banjo bolt.
-crack open the bleed screw and slowly inject brake fluid. it helps if you have another set of eyes to tell you when the fluid comes out the reservoir because you'll probably have your eye on the bleed screw to make sure you don't inject air and aren't leaking fluid everywhere.
-Once new fluid is filling up the reservoir switch to the other caliper.
-repeat the injection processs. Once fluid is filling the reservoir start working the fluid both ways. inject it from the syringe, and push it back down from the lever. you can leave the bleed screw open during all this. the idea is to just work the fluid back and forth in the system to try and move any air bubbles.
-Repeat the back and forth process on the other caliper.
I figure if you can move enough fluid back and forth (it really doesn't take much to fill the lines) and have no air bubbles coming out either end you should be good.
I did this with the rear brake also, however because it looks like the banjo is higher than the bleed screw i filled up the reservoir with new fluid. Attached the syringe to the bleed screw. Applied vacuum. and crack open the bleeder, keeping an eye on the fluid level in the Res. inject it back in if it gets dangerously low.
you'll always want to have the wrench for the bleed screw handy so you can close off the bleed screw if you ever need to abruptly stop fluid flow to avoid sucking in air.