Honda CBR 250 Forum banner
1 - 20 of 31 Posts

· Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
So i have a cbr250r abs 2013, 3 months ago while riding, suddenly my front brake lost nearly half of the pressure. The could pull the lever all the way through. I gave it to a trusted mechanic and he said he did something (didnt charged for it). And the issue went away. Now again the same problem happened again. The longer I ride, the more pressure i lose.
Front tire was also running tight so i got the pistons cleaned up and and tire was rotating freely again. Then he said he removed some air from the system and the brake became perfect again. He said if it happened again, master cylinder will need a rebuild or replacement. Can you guys enlighten me what might be the cause, if its master cylinder culprit or anything else.

Also, can a NON-ABS rebuild kit work in ABS master cylinder? I couldnt find a rebuild kit for specifically ABS model.
Thank you in advance.
Font Household hardware Audio equipment Portable communications device Fastener
 

· Registered
Honda: INNOVA125i(2010); CBR250R(2013)
Joined
·
1,075 Posts
According to Pertzilla's website, OEM parts, these are two "different" kits with a different catalog number and a different price:
For CBR250RA (ABS) - LINK: 45530-471-831 43.20USD Does not include shipping
For CBR250R - LINK: 45530-KVY-911 16.23USD Does not include shipping

According to Wemoto's website, TRK parts, these are two identical kits with the same catalog number and the same price:
TRK (AC7400) ~20USD Does not include shipping
LINK to CBR250RA (ABS)
LINK to CBR250R

In both stores you can find excellent customer service, you can e-mail to them and ask them.
 
  • Like
Reactions: Mory

· Registered
Honda: INNOVA125i(2010); CBR250R(2013)
Joined
·
1,075 Posts
  • Like
Reactions: goool89

· Registered
Honda: INNOVA125i(2010); CBR250R(2013)
Joined
·
1,075 Posts
Im from India so shipping is gonna cost me more than the product itself
At Thailand you have an excellent prices too.
Super-Bikers also has an excellent online store:
LINK1 ABS (45530-471-831 26.26USD) Does not include shipping
LINK2 (45530-KVY-911 5.15USD) Does not include shipping
Rectangle Font Communication Device Parallel Screenshot
 
  • Like
Reactions: goool89 and Mory

· Registered
Joined
·
116 Posts
By chance are you doing a lot of riding on dirt or broken-up damaged road? I noticed your Indian flag and I understand the roads aren't the best there. It could be you're just sloshing up fluid on bumpy roads and pumping bubbles into the system every time you brake. If that's the case you might remedy the problem by filling up your brake reservoir completely with DOT4 (or appropriate type) brake fluid as close to full as possible without spilling. You must remember to remove the fluid before your next brake change. You will also be able to determine if you're leaking any fluid out of the system. At least you can rule out fluid-loss or air penetrating into the system.

Maybe you bumped a banjo-bolt loose or unseated a crush washer. You can buy them in bulk cheap. Maybe confirm the fluid is the correct type and not eating the seals on the pistons on the levers and at the calipers.

If you're not losing fluid but still getting air, my money would be on bumpy roads and pumping bubbles into the system.
 

· Registered
Joined
·
11 Posts
Discussion Starter · #9 ·
Thanks for replying, actually the roads are not that bad as you're saying and I have been riding since 2018 and this issue occured just now. No offroading done.
Also no leakage of brake fluid at all. I guess master cylinder is the main culprit.
 

· Registered
Honda: INNOVA125i(2010); CBR250R(2013)
Joined
·
1,075 Posts
The longer I ride, the more pressure i lose.
no leakage of brake fluid at all
I guess master cylinder is the main culprit.
YES
Sometimes a few activations, pumps, of the brake lever will restore the pressure, but as you apply force on the lever the pressure drops again. Of course you shouldn't drive like that.
In most cases, the cylinder, the bore, was not damaged, and the complete piston kit is replaced, or only the two seals of the piston.

To remove the CIRCLIP (90651-MA5-671) that holds the piston, you need a special tool (e):
Internal Snap Ring Plier with a narrow and long nose.
 
  • Like
Reactions: Mory

· Registered
Joined
·
11 Posts
Discussion Starter · #11 ·
YES
Sometimes a few activations, pumps, of the brake lever will restore the pressure, but as you apply force on the lever the pressure drops again. Of course you shouldn't drive like that.
In most cases, the cylinder, the bore, was not damaged, and the complete piston kit is replaced, or only the two seals of the piston.

To remove the CIRCLIP (90651-MA5-671) that holds the piston, you need a special tool (with a narrow and long nose): Internal Snap Ring Plier
That is exactly whats happening. Pumping restores it temporarily but it loses pressure as soon as i brake for real. I will change the cylinder as soon as i can find it. Thanks
 

· Registered
Joined
·
116 Posts
Strange. If air is getting into the system through the master cylinder, fluid should be leaking out through the master cylinder. The fix is probably just a simple rebuild. Maybe air isn't the problem after all.

If you have the know-how to pull out the piston, you could inspect the two rubber rings. It may be possible to rejuvenate them.
 

· Registered
Joined
·
7 Posts
I have a cbr 250r Abs 2012.
So apparently I was riding 2 weeks back and my front brake loses the pressure like half the lever was sinking inwards. I approached my mechanic and he suggested me the same to change the master cylinder repair kit I found it and got it changed. After changing it in about 4 days and lever sinked again. I got another master cylinder repair kit and got it replaced thinking it be a fault repair kit. Same happened again and this time the lever lost all the pressure, pressing it fully had zero impact on braking. Then my mechanic suggested to change the whole front brake assembly (reservoir, switch, master cylinder) i got the whole kit and got it replaced and after 6 days my lever still loses all the pressure. Have zero clue what to do now. Seeking answers i found this thread. I hope some of you might be able to help me. Thank you brothers.
 

· Registered
Joined
·
3 Posts
I have a cbr 250r Abs 2012.
So apparently I was riding 2 weeks back and my front brake loses the pressure like half the lever was sinking inwards. I approached my mechanic and he suggested me the same to change the master cylinder repair kit I found it and got it changed. After changing it in about 4 days and lever sinked again. I got another master cylinder repair kit and got it replaced thinking it be a fault repair kit. Same happened again and this time the lever lost all the pressure, pressing it fully had zero impact on braking. Then my mechanic suggested to change the whole front brake assembly (reservoir, switch, master cylinder) i got the whole kit and got it replaced and after 6 days my lever still loses all the pressure. Have zero clue what to do now. Seeking answers i found this thread. I hope some of you might be able to help me. Thank you brothers.
Danny, your mechanic is right.
It is possible that the new kit will be damaged.
It is possible that the second new kit will also be damaged.
It is possible that you will replace the entire unit for new one, and it will still be damaged.
Is it reasonable? The answer is: No.
Maybe it should be recorded in the Guinness book?

If there is a loss of pressure and the lever sinks, this only happens in one of the following situations:
(1). There is a leak, and brake fluid is coming out of the system (dripping out).
(2). There is a compression leak in the pump and fluid returns back to the reserve tank.

In your case I understand that there is no leakage. So what do you do now?
Answer: What you did before, sorry, your mechanic is right.
At some point, statistically, you will be able to buy a good new kit.
 

· Registered
Joined
·
7 Posts
Danny, your mechanic is right.
It is possible that the new kit will be damaged.
It is possible that the second new kit will also be damaged.
It is possible that you will replace the entire unit for new one, and it will still be damaged.
Is it reasonable? The answer is: No.
Maybe it should be recorded in the Guinness book?

If there is a loss of pressure and the lever sinks, this only happens in one of the following situations:
(1). There is a leak, and brake fluid is coming out of the system (dripping out).
(2). There is a compression leak in the pump and fluid returns back to the reserve tank.

In your case I understand that there is no leakage. So what do you do now?
Answer: What you did before, sorry, your mechanic is right.
At some point, statistically, you will be able to buy a good new kit.
I will try a trusted kit tomorrow, and will keep you guys posted. Thank you so much for replying
 

· Registered
Joined
·
116 Posts
...my mechanic suggested to change the whole front brake assembly (reservoir, switch, master cylinder) i got the whole kit and got it replaced and after 6 days my lever still loses all the pressure.
I'm pretty sure the problem is your mechanic.


Remaining issues (assuming the mechanic did his job correctly): Not using crush-washers on the banjo bolts, reusing old crush-washers on the banjo bolts, not torqued correctly at the banjo bolts, not recognized a worn out hose, not recognized a cracked caliper, not recognized leaking piston seals, not recognized pitted pistons.

I would recommend replacing the caliper seals, it's an easy job if you know how to bleed the system. It will give you an opportunity to physically inspect the caliper, rubber rings, and pistons for pitting. I'm surprised he jumped right into replacing the expensive stuff rather than just give it the required maintenance.

This is why force myself to learn how to do this stuff. You are entitled to a refund, or at least have him return the parts he replaced. If he is like most mechanics this won't happen and he is happily spending your money as I type this. You paid for a qualified mechanic to diagnose and repair the problem, but you received a guy that would only make guesses. You intended to pay for a repair, not an attempt. I'm sorry you're having a bad experience. I wish there was more we could do for you. Without actually pressing the handle to see what you are experiencing, what you describe sounds like air is slowly getting into the system rather than fluid pushing past the rubber seals.
 

· Registered
Joined
·
116 Posts
Highlighted in yellow are the remaining parts which can leak. At the caliper in photo 1 is the most likely problem. Item number 1 (piston seals). These are supposed to get replaced periodically. Item 5 often fails as they get pitted over time. Item F-5 (Caliper) can get chunks of dirt in them especially when you push in dirty pistons when changing brake pads. Item 3 (bleeder bolt) can introduce a leak. Failures of any of these part can let fluid out of the system or let air into the system.



Map Font Parallel Auto part Illustration


In photo 2: Crush washers (part 18) are disposable and should only be used once. Trying to re-use them can prevent them from sealing. Banjo Bolt (part 17) can have damage allowing air/fluid in or out. The hose on part 2 can be aged or damaged releasing fluid or allowing air to enter.
Map Organism Font Slope Parallel



Brakes look complicated but they are a very simple device when you understand how they work. 99% of the time they just need a rebuild. Since the master was rebuilt already you just need to do the Caliper. This just entails replacing the 4 rubber rings, inspect and wipe the pistons with a clean towel, and installing new crush washers. Pistons (part 5 photo 1) should look shiny and polished like your forks. It is cheap maintenance.

EDIT
It is possible the wrong DOT brake fluid is eating away at the rubber seals.
 

· Registered
Joined
·
7 Posts
Highlighted in yellow are the remaining parts which can leak. At the caliper in photo 1 is the most likely problem. Item number 1 (piston seals). These are supposed to get replaced periodically. Item 5 often fails as they get pitted over time. Item F-5 (Caliper) can get chunks of dirt in them especially when you push in dirty pistons when changing brake pads. Item 3 (bleeder bolt) can introduce a leak. Failures of any of these part can let fluid out of the system or let air into the system.



View attachment 46067

In photo 2: Crush washers (part 18) are disposable and should only be used once. Trying to re-use them can prevent them from sealing. Banjo Bolt (part 17) can have damage allowing air/fluid in or out. The hose on part 2 can be aged or damaged releasing fluid or allowing air to enter.
View attachment 46066


Brakes look complicated but they are a very simple device when you understand how they work. 99% of the time they just need a rebuild. Since the master was rebuilt already you just need to do the Caliper. This just entails replacing the 4 rubber rings, inspect and wipe the pistons with a clean towel, and installing new crush washers. Pistons (part 5 photo 1) should look shiny and polished like your forks. It is cheap maintenance.

EDIT
It is possible the wrong DOT brake fluid is eating away at the rubber seals.
Thank you so brother for your input, i really do appreciate your effort. Can't be more happy to receive such a support.
.
Update :- removed the abs fuse. (abs not working now) ran the bike around 30kms the brake isn't losing pressure anymore.
What can be the probable issue in abs?
Can abs be repaired?
Or do i have to look for new abs unit ?
 

· Registered
Honda: INNOVA125i(2010); CBR250R(2013)
Joined
·
1,075 Posts
Cahuna & BG covered the issue very nicely.
If I understood, the thread opener does not have a problem with brake fluid leakage.
I'm not so sure about "easy job".
According to the manufacturer's instructions:
Handling the brake system requires a mechanical skill.
The brake system is a safety system and there you have to be even more careful.

If I understood correctly, the thread opener buys parts himself and does the work himself, and has a mechanic that he consults with. But maybe I misunderstood?
It is possible the wrong DOT brake fluid is eating away at the rubber seals.
As long as it is correct DOT brake fluid, it will not cause any damage to the rubbers.
The manufacturer sets the standard for our CBR250R(2011-2013) brake fluid to: DOT3 or DOT4
It is forbidden to mix different types, and must be replaced every two years.

Brake fluid absorb moisture to it, so failure to replace it on time can destroy(by rust) the metal and aluminum parts,
and destroy seals that wear out because they friction on the damaged metal surfaces.

Updating
Moisture in the brake fluid is also dangerous because it lowers the boiling temperature, (when the fluid boils it turns into a gas, which causes a complete failure of the braking system)
 
  • Like
  • Helpful
Reactions: Mory and BG44

· Registered
Joined
·
7 Posts
Cahuna & BG covered the issue very nicely.
If I understood, the thread opener does not have a problem with brake fluid leakage.
I'm not so sure about "easy job".
According to the manufacturer's instructions:
Handling the brake system requires a mechanical skill.
The brake system is a safety system and there you have to be even more careful.

If I understood correctly, the thread opener buys parts himself and does the work himself, and has a mechanic that he consults with. But maybe I misunderstood?

As long as it is correct DOT brake fluid, it will not cause any damage to the rubbers.
The manufacturer sets the standard for our CBR250R(2011-2013) brake fluid to: DOT3 or DOT4
It is forbidden to mix different types, and must be replaced every two years.

Brake fluid absorb water to it, so failure to replace it on time can destroy(by rust) the metal and aluminum parts,
and destroy seals that wear out because they friction on the damaged metal surfaces.
Hello sir
Yes i buy the parts myself but installation done by a professional. I do consult him and buys the part he ask me to.
A pay close attention to everything he tells me I question him and look out for what he's doing.
I only use dot 4 brake fluid from a reputed brand and from a sealed container.
Even before my bike had this problem i regularly changed brake fluid every 9th month as i mostly ride in city traffic.
 
1 - 20 of 31 Posts
Top