Hey, so I'm well on my way o my handlebar swap, though it seems I need a brake hose and clutch cable from a pullback model.

I've been reading about draining the fluid and understand that the master cylinder should never be left to dry out. That leaves me wondering how I would replace the hose. Seems to me that as soon as I crack the bolts open it will empty.

Hope someone can guide me on this one. Clutch cable seems straightforward.

The caution to never let the Master Cylinder "dry out" - is for those folks changing brake fluid or doing other maintenance work.....the caution is to prevent you from getting any air in the system.  However....installing a new hose will cause a complete hose that is full of air.

You will need to install new fluid and bleed they system once the new hose is installed.  As Verslagen has said, having a vacuum bleeder makes it a bunch easier.

Or.......

https://www.youtube.com/watch?v=ZMv9l7tIfMQ


I use aquarium pump check valves for the bleed hose....I have been using the same pair for more than 30 years.  Once done bleeding wash the check valves and tubing out with soapy water, and then let them dry before putting them away.  You might be able to find these at a pet shop or store that specializes in aquariums.

http://www.ebay.com/itm/2-Pack-3-8-Viton-Kynar-Non-Return-Marine-Aquarium-Che...

The best way to be neat about it, would be to turn the handlebars to make the reservoir cap as level as possible, then take off the reservoir cap and carefully wipe all the brake fluid off the top.  Then apply some packing tape or very wide masking tape over the reservoir to seal the top.  Then get a container and disconnect the bottom of the brake hose at the caliper....and catch as much of the brake fluid as you can.  When it stops dripping then loosen the fitting at the master cylinder....and the hose will then drain the brake fluid into the container.  You can then remove the brake hose, you should get little or no flow out of the brake master cylinder...as the tape will not allow the master cylinder to vent and drain.  You can never be completely clean about it however....and be sure to have an old T-shirt or two to wipe up the fluid....the cotton works a lot better than paper towels on brake fluid.

Then you can remove the old hose, install the new one, and begin the bleeding process.  When you remove the tape over the master cylinder and open the bleed screw at the bottom...be sure to keep the master cylinder from getting empty at anytime during the bleeding process, as that will allow more air into the system and require more bleeding.  After you have ridden the bike for a day or two..it never hurts to bleed it one more time - as tiny bubbles can get into the brake fluid while you are bleeding, and after the bike sits for a while the tiny bubbles will collect in the high points.

That really helps. Although the MC is already off the bar and the bar is off the bike. But I can get help holding it upright until I drain the hose and connect the new hose. Now will a tool like the one linked above help with bleeding?

sesamestreet wrote on 03/26/15 at 05:49:18:

Now will a tool like the one linked above help with bleeding?

Yes. But a syringe can be used instead of the pump, an empty bottle can serve as the "collection container" in the kit and a few lengths of hose of various sizes can provide you with adapters. The kit has everything you need for $25 (I think HarborFreight has the same kit) or you can source your own for $5.

Same method, different price point.