Motorcycle Brake Without Pressure Point

Hello scooter riders,
"My colleague has a CBR 900 from 2001, and the front brake doesn't develop a proper biting point. If the motorcycle stands for a longer period (e.g., overnight), and you then pull the brake lever, you can pull it about halfway before feeling something like a pressure point. However, if you pull it tighter, you can almost pull the brake lever all the way to the handlebar. Despite these issues, if you ride the motorcycle, a normal biting point will develop after a few kilometers. The brakes themselves have been fully functional from the beginning."
The brakes have been bled several times without any change. Yesterday, we replaced the standard brake hoses with stainless steel braided lines. Brake fluid was drawn from top to bottom using a vacuum pump. Even that didn't resolve the issue.
Do you have any ideas on how to tackle this problem?

Hello Thomas,

I'm not familiar with the specific brake system used, but: if it's a floating caliper brake, you should check the caliper guides to ensure they move freely.
The brake may also be incorrectly assembled, so please be careful!

Best regards, Rainer.

Hi!

The CBR doesn't have a floating brake caliper; instead, it has two discs that are mounted on floating supports. I think Rainer might be onto something. Check if the discs can move freely within their mounts. Also, inspect the pads. If there is significantly uneven wear, an effect similar to what Rainer described could occur. One of the pistons will be pushed back further than normal due to the seemingly off-center disc, which increases the travel distance.

Best regards,
Uwe

-> Disassemble and check all pistons for smooth operation. Inspect all seals (check for play). Pistons can sometimes seize, which usually doesn't affect braking performance but does impact the lever travel and, of course, the wear pattern on the pads. I experienced this with my bike after 2 years...

-> leave the stainless steel flex hose as is.

The window brackets rarely have anything in them.

CU Gremlin.

"Thank you for the tips. We took a closer look at the braking system yesterday and found the problem. The CBR has two-piece brake calipers, each attached with 4 screws (M8?). In any case, when you pull the brake lever, you can see that the caliper expands slightly because the screws are stretching."
Remedial measures:
1.) Tighten screws.
2.) Screws with higher strength --> more force is required to stretch them.
3.) Most expensive solution: One-piece brake calipers from the aftermarket accessories market.

Yesterday, we only tightened the screws. Subjectively, this already resulted in a slightly more defined pressure point. However, it's still far from the level of other athletes.