[BG44]

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.

 

[BG44]

You might not know this but in India here there's problem of recieving replica of the spare part you are buying. That's my i go the extra mile to make sure that the item i am gonna get installed in my vehicle is original and genuine product. Hence i buy the spare parts myself. I am sorry if i mis- understood what you were trying to say.
I really hope that you would help me resolve the issue.

I don't think your situation is different from anywhere else in India, or anywhere else in the world.
No mechanic likes when you buy your parts yourself and bring them to the mechanic to put them on your motorcycle. Because mechanics have an extra profit on the parts.
You want a cheap repair, OK, get a cheap service. I think everything is fine
That's why I suggested you to keep doing what you're doing so well. all is fine.