Post by willy3pigs on Jun 9, 2024 20:14:39 GMT
I've Chinese aftermarket master cylinders on both my 250 and 400 Honda's, and though they both started out just fine they have both developed problems after a couple of months.
On the 400 you get about ten stops until the lever stays back to the bars if you apply the brakes in quick succession, then it takes 60 to 90 seconds for the lever to slowly return to the fully extended position. If you're bimbling along country roads as I do this is not too much of a problem but does need sorting.
The same type of master cylinder on the 250 has the problem that the position of the lever gradually works its way back to the bars over an extended period, the brakes work consistently but after say a 500 miles worth of use the lever has moved back enough that the brake light is constantly on.
I first stripped the 400 brake to find that the front seal on the piston had lost over a third of its sealing lip, and appeared swollen, then the 250 master cylinder was dismantled to reveal the 14mm front seal had swollen to 16.3mm. The attached pics show both the front seals, the damaged seal from the 400 master cylinder is noticeably a bit smaller as it was removed and wiped clean of fluid a few weeks ago and has shrunk back to nearer its normal size the other seal from my 250 has only just been removed.
I have just fitted a replacement piston and seal set shown in the pics which came with a noticeably more powerful return spring, I just hope the seals are proper EPDM rubber this time, as I've no doubt its the swelling of the seals that's the cause of the problems..
On the 400 you get about ten stops until the lever stays back to the bars if you apply the brakes in quick succession, then it takes 60 to 90 seconds for the lever to slowly return to the fully extended position. If you're bimbling along country roads as I do this is not too much of a problem but does need sorting.
The same type of master cylinder on the 250 has the problem that the position of the lever gradually works its way back to the bars over an extended period, the brakes work consistently but after say a 500 miles worth of use the lever has moved back enough that the brake light is constantly on.
I first stripped the 400 brake to find that the front seal on the piston had lost over a third of its sealing lip, and appeared swollen, then the 250 master cylinder was dismantled to reveal the 14mm front seal had swollen to 16.3mm. The attached pics show both the front seals, the damaged seal from the 400 master cylinder is noticeably a bit smaller as it was removed and wiped clean of fluid a few weeks ago and has shrunk back to nearer its normal size the other seal from my 250 has only just been removed.
I have just fitted a replacement piston and seal set shown in the pics which came with a noticeably more powerful return spring, I just hope the seals are proper EPDM rubber this time, as I've no doubt its the swelling of the seals that's the cause of the problems..
