Modern Vespa

I've been trying to bleed the brakes on my BV350, using the vacuum (Mity-Vac) method. Any way I try, I seem to suck more air than fluid out of the caliper bleeder. I'm keeping the reservoir filled; no air is getting in there. Yet, I can never get to the point of having pressure at the brake lever. So far, I've been working on the rear brake only.

My suspicion is that air is leaking around the threads of the bleeder screw whenever I open it. How do you get a tight seal all through the system so you can suck fluid all the way down from the reservoir? I've seen suggestions online to put grease around the bleeder screw or plumber's teflon tape on the treads. Does this make any sense?

I've also tried the squeeze-the-brake-lever-open-and-close-the-bleeder-screw method, with no luck.

Does anyone have a better way to bleed brakes?

2013 BV350, without ABS.

The Scooterville Method?

You have to be sucking air as described, but other than teflon/grease I'm not sure what else you can do. I'm not sure how touchy the opening of the nipples is...obviously there's a sweet spot of open enough to get fluid out but not too much to have too much play around the threads for air to enter.

So, swearing doesn't help?

This is why I pressure bleed from the bottom.

Please tell me more. How does that work?

Suck what you can out of the brake fluid reservoir (top side, at the lever).
Fill a big syringe with brake fluid, and get the air out of the ~6" or so length of clear hose you attach to it.
Attach the other end of the hose to the brake bleeder.
Open the bleeder. I suck a little into the syringe just to be sure the bleeder is open.
Push all that nice clean brake fluid into the brake system. From the bottom.
Close the bleeder.
Check the fluid that has filled the reservoir. If it's clear, you're done. If not....

Thanks! If that doesn't work it's off to Scooterville.

Do you need to squeeze the brake lever to open the pump?

Nope.

Put it this way. When you replace the brake pads, you push the piston back into the caliper. This pushes brake fluid back up the line. This is the same, only different...

It will be superfluous to repeat it but it would help, if possible, to shoot videos or photos of the maintenance operations and accompany them with descriptions; if there is something wrong or that can be improved, it will be easier to come to the rescue or advise.
PS: remember that brake blood is corrosive to painted parts.

I spent two days bleeding the brakes on my BV350 after getting air into the system from an unknown source. And was, eventually, mostly successful. I also started out with a vacuum pump. Big mistake.

Note that there is a proportioning valve under the front cover, with its own bleeder screw, that proportions pressure between one piston on the front caliper, and the rear caliper. Seems to be a good place for air to hang out.

If I had a dealer in the area that would do it, I'd take it in. Sadly, locally, I do not.

Piaggio did a good job of NOT putting the bleeders screws at the highest part of the calipers, NOT routing the lines so the caliper is at the lowest point. Easy to get air in, not easy to get it out.

If you do the back-bleeding method, almost certainly will want someone helping you, keeping an eye on the reservoir level and sucking out brake fluid as needed so it does not overflow.

I'm guessing the dealer has adaptors for the reservoirs so they can pressure-bleed the system from the top. The idea, whether pressure-bleeding or back-bleeding, is to move fluid through the system fast enough that it carries any air along with it. Give the air a chance to rise through slow-moving fluid, and it will almost certainly find a nice high spot to hang out.

As I mentioned elsewhere, I ended up taking the calipers off, inserting wood spacers so the pistons were retained, and holding them so the bleeder was at the highest point.

Next time I'll get someone to help, be very careful to keep pressure on the lines at all times. If that fails, I'll borrow a pressure bleeder and make some adaptors.

If you search about BV brakes. You'll find out how clueless dealers(not all) can be.

If you suck the reservoir fluid out with a syringe, it will tell you how much is there and then you'll know how much you can pump in.

I have a special pressure bleeder that hooks up to a garden sprayer that's connected to a plate that bolts on where the reservoir cover is. One of the few perks of being a machinist. I got the idea off YouTube.

I have never had an issue bleeding the brakes on my '13. Just keep the fluid moving and don't let any air get into the system.

Great advice to a person who's already got air in the system.

I expect to be very careful next time, and hopefully avoid problems. But the system seems to admit air fairly easily, if you try to use a vacuum pump to bleed it. And once air is in the system, devilishly difficult to get it out without pressurized fluid being externally applied from one end or the other.

Simply pumping the lever, sufficient on every other bike and scooter I own, will not get the job done.

Maybe need to start a Beverly Owner's Group (BOG?) and chip in to buy a pressure bleeder with the appropriate adaptors that we can pass around?

Bleeding brakes is easy for me, it's taking apart the headset to get to the reservoir that sucks the big one

I know Jimding has seen this pic. After clearing the air in the sprayer valve, you push the adapter hose on the barb fitting. put a 4" hose on the bleeder screw so you can see fluid. Crack the bleeder on the plate to bleed the air out of the reservoir. Tighten the bleeder and open the caliper bleeder screw, push the sprayer valve and pump the brake lever until clean fluid exits the caliper.
After the system is clean. Disconnect the sprayer and use a syringe to suck out excess fluid in the reservoir so you can pull the bleeder plate without fluid pouring out.
Set the fluid level and replace gasket and cap. Clean up and then you get the pleasure of replacing the headset

OOPS! Don't let the sprayer pressure go above 20PSI.

Did you make that or buy it?

If he did it:
To: genius
B: I want to see the sectional drawing

Made it. Wouldn't be worth selling. I'd have to sell 100s of them to get the cost down. Besides, I'm semi-retired and full retirement can't come soon enough.
Can't put a video on GoogleTube, I'll be damned if I'm going to pay to be a good Samaritan.

Was the body machined from a solid piece using a milling machine tool?
I am familiar with this type of work.

Sorry, i just went thru my home projects on AutoCAD and can't find it. If I remember I'll check my work computer but don't get your hopes up. If life doesn't get in the way of living, I might remember to redraw it and post it as a PDF.

Solid piece. I needed room to design the reservoir bleeder screw. You'll have to check GoogleTube for the garden sprayer. You'll have to add a valve stem to it to check the pressure.

I did get some air in the system the first time I did it. I have nice hand vacuum pump that did nothing to help me, and a cheap $25 harbor freight compressed air driven vacuum bleeder that corrected the problem without issue. I really don't know what the big deal is. I've bled far more difficult systems than this.

Update: I tried Madison Sully's pressure method and still have a little air in the rear brake system. Bueller, which of the HF bleeders do you have? I see they now have two pressurized and two vacuum bleeder kits. Does it work from the caliper end or the master cylinder? Thanks.

Funny thing, I bled the brakes on the BV350 once before and didn't have any issues. Must have been lucky.

That's a magnificent piece of aluminum, but using the original reservoir cover as a template, couldn't you make the same gizmo out of a 1/4" plate cut with a hacksaw and tapped for the fittings?

I have one of their vacuum bleeders that connects to compressed air to create the vacuum.

One of the other things you can try is to have someone RAPIDLY pump the brake lever, letting it return fully before each pump. Then hold it firmly while you crack the bleeder screw. Do this several times in quick succession and you may force the air out. Obviously you will want to do this with a full reservoir and the cap installed or you are going to wind up with a mess.

No. It's all about the bleeder. Unless you have a better way to bleed the reservoir. You don't want air in the reservoir during the pressure bleeding. When there's a clear tube on the reservoir bleed screw, you can see when the air is out of the reservoir
Even the barb fitting is 1/8 N.P.T. and needs more than 1/4" thick plate. You'll just have to wait till I go to work Saturday for a drawing. If I remember.

I might be missing something, but it would seem to me that if:
* the base of the barbed fitting extended well through the plate, near the bottom of the reservoir, and
* the base of the bleeder valve extended barely through the plate

Then it would be possible to tilt the bike a little so any air in the reservoir could float up to the bleeder and be released, and there would be enough horizontal distance between the two fittings' bases that any residual air would be immaterial to the bleeding process.

A'ight. Next time I suggest that I come up there and stand by nursing a beer, mumbling words of encouragement and random advice on putting a finer edge on cursing....

At risk of being a bragger. I have experience in design, drafting and prototyping.