Bernie's budget beast boasts brakes! (Couldn't help myself.)
Man, I hate bleeding brakes. I always make a mess.
The front master cylinder and caliper was pretty straightforward- once I realized that the throttle assembly was preventing full swing of the brake lever:
Once the throttle was removed (Thankfully, the carburettors aren't installed yet.) it was easy peasy. Using the apply brake, loosen bleeder, tighten bleeder, release brake for a second and repeat method, I spilled only a few drops on the wheel rim and the floor when removing the bleed line at the caliper.
The integrated brake system was another story.
Using the same method, I bled the brake pressure regulator, the front caliper and then the rear caliper. Hung the front caliper way up so that it's brake line was sloped upwards to the caliper and had the bleed bottle on a ladder:
Detached the rear caliper and again oriented it to have the bubbles rise up to the bleed screw.
Got plenty of fluid through.
But the brake lever was spongy and worse, once I had it pumped up it would slowly sink under constant pressure.
Then I noticed a drip from the brake regulator. Removing the top rubber cover:
How did the circlip come loose?
I removed the regulator to find out what had happened. More drips from the disconnected brake lines.
I couldn't see anything wrong, so I decided to replace both internal o-rings. I carefully measured the groove diameters, ODs and the thickness of the o-rings, made a sketch of the dimensions, and then cleaned and bagged the relevant parts to bring to the parts counter of my friendly neighborhood bearing seller. They are always helpful, but it might be tough finding the correct size. Five minutes after entering the place, I had the 0-rings in my hands. General Bearing Service in Ottawa is the best.
Reinstalled the regulator bled everything again and crap. The brake lever still fell with constant pressure. I've seen this before and it's always a bad master cylinder. Was the rebuild kit I used bad? Did I miss seeing a scratch in the master cylinder bore? It had been a long day, I was fed up, so I went on to the MG Cycle site and went to order a new master cylinder. Double crap. "This part is out of stock. We'll let you know when...".
The next day, I decided to bench test the master cylinder with an old brake line connected to it, pinched shut by locking pliers.
And it was fine! WTF?
I researched a bit more- it looks like reverse bleeding could be the solution. Connect a syringe of brake fluid to each caliper in turn and bleed fluid out of the regulator bleed screw. But what a mess. Brake fluid dribbling out around the caliper bleeders, brake fluid sprayed because I forgot to release the syringe pressure before disconnecting it and holy cow, brake fluid overflowing out of the rear master cylinder!
Anyway, it worked. Let's just say my experience would have made a great advertisement for paper towels. And kitty litter. The Guzzi can now stop. Hopefully soon, it will be able to go.
Thanks Charlie, (Antietam Classic Cycle) for the caliper pin!