A front brake bleeding annoying issue.

Jury Duty and trial completed so getting back on this issue, which is concerning me more and more. It is definitely not an air gap issue in the line somewhere as that would just result in a spongey feel to the brake lever that would remain constant.

There is definitely something wrong with my master cylinder. On hot days while parked, the first pull of the brake lever has almost no resistance for the first 3/4 of travel, then the lever sticks there. It feels like the lever is traveling freely, like there is no fluid being pressurized at all. At the 3/4 point of travel the actual lever sticks and does not return back on its own. I have to pump the lever 3 to 4 times to get it to return to full release position and to regain normal brake lever pressure / feel. It feels like when you are pressurizing a new brake system with fluid for the first time. The first few pumps are limp until the piston pulls in and pressurizes enough fluid to make the brake lever feel firm.

I also opened the master cylinder to see if there was a bubble around the piston opening area at the bottom and could find none.
This is very concerning so I am going to the dealer to pick their brain on this issue. Seems like there may have been some percentage of defect in these front cylinders that may have slipped through manufacturing. If the Honda mechanics scratch their heads on it too, I am going to buy a new master, to replace my already "new" master.

 

Have you tried taping back brake lever and leaving bike on side stand?
Vacuum bleeding could help.
Are all bleeders tight just a though.

 

I have zip tied the lever back and left it a couple of hours to see if the zip tie loosened and it didn't....so no leaks and yes the bleeders are tight and no air in system. No leaking anywhere in the system. I have a feeling this is one of the reasons the previous owner only kept the bike for two weeks then sold it right away. The bike was in Alabama and it was hot there every day according to the seller. "Intense heat" were his words.

I uploaded a video of the issue to YouTube so I can show my Honda dealer what I am experiencing. The temperature was 85º for a few hours when I took the video, so the lever only moved about 1/2 loose travel back. On hotter days in the 90º's, it goes back 3/4 loose travel before stopping. I have had it pull almost to the hand grip on 100º + days ( which is very rare here ).

See link for video. : )

https://www.youtube.com/shorts/cE1Zise3Th8

 

What position is the lever in between 1-5

 

If you are talking about the cam adjustment for the lever, it is in the #2 out of 6 positions.

 

That it changes in the heat is very strange. Perhaps there's a comtaminant in there? Water? Damaged hose that gets less rigid when hot? How about if it is cool olut but you work the brake a lot so that ambient air stays cool, but braking components and fluid get hot? What does it do then? Are you sure that everything is working as expected in calipers and master? Very strange. I've never had this on any bike, regardless of PO crap work.

 

Past due to take this master apart and investigate.

 

Try position #1

Have you checked that the pads aren’t moving in when you pull the lever?

I get a similar thing happening when I’ve been using a lot of front brake in hot weather and then park the bike up, the discs and pads swell with the heat of 4 pistons per caliper then cool down to leave a gap

 

When I first pull the lever it isn't pressurized so nothing could be moving.
My video has over 615 views on You Tube in 24 hours so I'm thinking someone may have solved this issue already and reply.
I'm going to show it at my Honda dealer this weekend.

 

A braking system is not pressurized at rest. If it is, something is wrong. If you have to pressurize it to get it to work, something is wrong.

 

It has to be something that doesn't cost money or require anything to be taken apart.

 

Never heard of pad knock back then …