Custom Motive Power Bleeder Adapter for VFR

I always found bleeding brakes a PITA until I bought the power bleeder, but that only had adapters that worked with the cars/trucks, not the two bikes we have.

The power bleeder can be purchased with an adapter for your vehicle, or
by itself (click here).

Unfortunately, not adapter exists for motorcycles (that I've found).

So I purchased a spare master cylinder cover for my '86 VFR, and used that as a base for making my own adapter.

I picked up some clear tubing (1/4" ID), and a few 1/4" hose barb to MPT fittings. I drilled a hole through the cover, teflon taped the snot of out of the fitting, and screwed the brass fitting into the aluminum. Doesn't quite fully seal, but that's easily fixed. Then I cut a seal out of neoprene, to fit under the cover, with holes for the screws and for the fitting. Needed to stack two of them to get the thickness right, and a good seal around the reservoir.

I'll attach some pics later (after I go take them).

To do it over again, I'd have picked up a piece of nylon, say 2x4x1/4", and used that instead of the new cover. I could have drilled and tapped that for the fitting, and gotten a better seal. But that would only have worked due to the flat top of the reservoir. I'd been thinking along the lines of a modified cap as that's what the cars use, and for any bike with a screw-on cap (like the rear brake master uses), you'd need to go that route as well.

However, even with it only holding about 5psi before it starts to leak, it works like a charm. I first pushed all the old fluid out with just air (while testing the seal of the system), and then used fluid to flush out all the air. It's amazingly how quickly it purges all the air of the system, and how much cleaner the fluid is afterwards (my clutch slave rusted, and the fluid in the master turned orange, once upon a time, and it's never really been clean since).

This is FAR preferable to doing it by hand, and I think it does a better job.

 

I tried a pump-style bleeder once, it sucked air in because I couldn't get it to seal with the bleed valves. I found it much simpler to just put the hose on'em and pump new fluid through using the master cylinder.

Why is monkeying around with a pump and Teflon tape "FAR preferable" to doing it by hand?

 

I have purchased a veterinary syringe and some nylon tube and reverse bled my clutch and brake lines from bone dry to air free in minutes.
The whole deal costs just a few bucks and when you're done you can toss it away. No clean up necessary. The method is positive pressure, so small system leaks are merely drips instead of inspirating air and causing trouble like a vac system can.
I probably save enough fluid to pay the cost of materials vs. top-down, the old school way.

Someone versed in top-down bleeding might cut me up with Occam's razor, but I've had trouble with that method, especially after a parts swap and dry lines.

 

If the pump attached to the bleed valves, it was probably a vacuum bleeder. This is a positive pressure bleeder that pressurizes the whole system, starting up at the master. Pushes the fluid through like the master would (except it can force the fluid through the master as well).

Building the adapter took a little bit of time, and the last time my clutch master was fully drained, it took an hour to get it primed correctly, so that I could start bleeding all the air out of the system.

I can setup the motive bleeder in <5 minutes, and then it will replace all the fluid in the system in a couple seconds once the bleeder is opened. You pressurize the tank, then open the bleeder valve, and air/fluid rushes out of the bleeder. I squeeze the lever a few times as well to work the piston back/forth, which gets the bubbles out of the master itself. Then close the bleeder, unscrew the top off the pressure tank, and remove the adapter and put the normal reservoir cover back on.

I prefer this to:

- squeeze lever and hold it
- open bleeder valve
- close bleeder valve
- release lever
- repeat (for 15 minutes)

It's less of a benefit on the bike as it is on the car (where you can't hold the brake pedal and get to the bleeder at the same time), but it's still a time-saver, and I think it does a better job than doing it by hand.

 

How do you deal with the mess at the master cylinder? or do you have the banjo disconnected from the master so that you can catch the fluid?

It definitely seems like a reverse bleed would work well for cleaning out the return port in the master. Maybe better than a top-down bleed.