Bleeding brakes
 

I was having a bear of a time bleeding the front brake on a scooter. Then I ran across this. Bled it in less than 5 minutes. Useful trick. Got the syringe at Ace Hardware.

How to reverse bleed a braking system - YouTube

i have heard of doing this, never had tried it though. ive got a vacuum bleeder i used. when it feels like ive got most of the air out, i zip tie the lever down for an hour and it lets the rest of the air escape back to the master cylinder.

Never tried the reverse method either.
I usually just let gravity do it's thing for half an hour while I do something else, then finish it off with the vacuum pump.

I had tried pumping, gravity the the vacuum methods with no success before this method.

Just about the smallest hydraulic brake system on the planet and such a huge problem :P

I thought you were cussing at your brakes, you being English and all.

You know what they say about scooters...:eek:

I don't know.

"Bleeding Brakes"
 

It is not the brakes that bleed but rather the knuckles if the wrench slips.

That's a good method for single line systems.

I have taken a long clear tube to reverse bleed a clutch and simply filled the tube nearly to the top with brake fluid and blown on it to push the fluid into the top of the clutch master. I first did this with my 74 Saab 99.

Ever since my Peugeot days, I have been a fan of reverse pressure bleeding. The clutch on the 504 could only be bled that way. I use a pump-type oil can that has never been used for anything except brake fluid. I just took advantage of the break in the weather and bled the brakes on my son't '86 Mustang GT. I had previously tried the regular method with no success. The pressure pump oiler got it done in just a few minutes.

This is basically how we do bicycle hydraulic brakes.

I haven't seen that method before. Thanks for posting the link. Can't figure how pumping the lever didn't do the job on a scooter. Does it have ABS or linked brakes or some other complexity in the braking system?

My Yamaha motorbike has ABS brakes and it's a bear to bleed. The ABS unit is under the seat, so the front brake lines run from the lever back under the seat, then up to the front of the bike and split to the calipers. The best way I've found to bleed it is to put the caliper bleeder under vacuum with a Mityvac, and then use the pump-the-lever approach. If you don't use both pressure and vacuum, air bubbles collect in the vicinity of the ABS unit and you end up with mushy (if clean) brakes.

Yes scooter has some kind of ABS. It's right next to the caliper. Maybe that's what it made it impossible to bleed using the traditional pumping method. I couldn't get any pressure to build at all the traditional way. I had dried out the master cylinder before using the syringe and my first push on the syringe sent a 4' high stream of brake fluid up out of the master cylinder after a few bubbles came out.