Hornet 900 brake is sticky

[max]

Wanted to ask for the experienced opinion of the group.

Just started to ride my hornet 900 ( 12 years old ) and the brakes although great in stopping power are stiffer to operate than the cb1100 ( 8 years old ).
Over some days i have had every single part of the front brakes, master and both 4 pot calipers ( similar to cb1100 ) apart, cleaned, greased and re-assembled, none show any signs of wear or damage, fresh brake fluid in the lines, bled all the air out and also replaced all the pads; it's better but still sticky .

#1 ;In the morning the lever takes more effort to operate and is slow to return. ( there is some extra play in the handle which slowly disappears as the piston slowly returns in half a minute or so.

#2; after a good couple of squeeze's it frees up to the point that it works acceptable enough and stays fine for some hours, but in the next morning........

#3; pretty sure i have narrowed it down to the master brake cylinder and the only culprits are the rubber seals on the piston.

#4; this has possibly been like this for some time but i started noticing it after comparing it with the cb1100 and another hornet 900 at a dealer closeby that works fine and operates light like the cb1100.

#5; the brakes drag slightly when stiff but release fine and run 100% clear when the lever feels free.

Anybody had a similar scenario and what was the cause?

[Houtman_imp]

Did you just clean the master cylinder using the old parts ?
After 12 years it probably is better to totally rebuild it with using NEW parts. Same with all the rubber parts on the calipers , new is better.

[pekingduck]

I'm not sure what you mean by "sticky" behavior, but a couple things come to mind. CB919 brakes, to my recollection, felt at least as good as the CB1100.
DOT 5 brake fluids may not be compatible with the rubber seals or with other brake fluids. Honda doesn't recommend it, only DOT 4.
The brake lever pivot bolt and lever tip are often overlooked as they may be dry and cause a "creaking" sound/feel.
When you say you used grease on the calipers, I assume that was only on the caliper brackets' sliding pins.
Everything may appear fine otherwise, including inside the chamber and piston, but caliper piston seals often have corrosive buildup underneath them that causes them to grab the piston too tightly.

[max]

problem solved;
it turned out that the low pressure seal on the back of the piston had swollen up to the point that it could not readily always return to the end of the stroke ( the return point )

After removing some of the seal that appeared a bit soft it is now running free again and the problem has cleared, the brakes are not dragging anymore!

Why did this happen? i probably caused it myself, i like to put some lubricant on the back part under the dust seal around the circlip area to prevent oxidation just in case some brake fluid seeps past the low pressure seal, i must have used the wrong type of lube that slowly reacted with the rubber and swelled it up over the years, the circlip area was well lubricated when i took it apart and i lubed it again but this time used " red rubber grease " which is especially made for these applications.

The brakes are now working fine, a lesson learned and a short video posted on YT.

https://www.youtube.com/watch?v=QM5Wh6Gs...e=youtu.be

By the way the master cylinder for these brakes is identical and use the same part numbers for the replacement parts
(master cylinder set 45530-ma4-671 )
as our cb1100's which is why i think this was relevant to post on the group.

Thanks for all the helpful replies from the members.

[Rocky_imp]

Glad to hear the problem has been solved.
I have a 2002 CB900F (919) and it has been flawless, but I was interested in this problem just in case I may also run into this situation at some point.

[max]

Thanks Rocky, very nice to hear from you and yes, the hornet 919 has been a very solid machine, not as good looking as the cb1100 but super reliable.

all the very best from New Zealand; max

[Rocky_imp]

Thanks Rocky, very nice to hear from you and yes, the hornet 919 has been a very solid machine, not as good looking as the cb1100 but super reliable.

all the very best from New Zealand; max

You too Max