RM 250 rear master has me stumped.

rc10andy
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rc10andy
Hi, I've got a leaky master cylinder that I can't seem to fix. I've had 2 new sets of All Balls seals to try and stop the leak. Both seals on the piston are seated with the wide end of the seal facing the spring and I believe this is correct. I've had new seals in my caliper and the brake hose is brand new also. I've cleaned the master cylinder out fully with brake cleaner and compressed air.

The leak I believe is coming from the M/C as fluid is running down my brake clevis. It will bleed up but then as soon as I ride it's pissing fluid out again until I have no brake within a lap or two.

Maybe the master cylinder needs replacing? Maybe I need a new piston?

Any help would be greatly appreciated. Thank you.
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kb228
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kb228 6/24/2019 3:13pm
6/24/2019 3:13pm
It could be that rebuild kit.
1
JohnCharlesC 6/24/2019 3:50pm
6/24/2019 3:50pm
Sounds like the only other thing is the banjo bolt and washers. That was what was causing mine to leak.
rc10andy
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rc10andy 6/25/2019 2:56am
6/25/2019 2:56am
kb228 wrote:
It could be that rebuild kit.
Well I was going to buy a different kit with a piston included rather than using my existing piston. It's not the banjo bolts and washers I don't think. Thanks for your reply
kb228
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kb228 6/25/2019 3:52am
6/25/2019 3:52am
kb228 wrote:
It could be that rebuild kit.
rc10andy wrote:
Well I was going to buy a different kit with a piston included rather than using my existing piston. It's not the banjo bolts and washers...
Well I was going to buy a different kit with a piston included rather than using my existing piston. It's not the banjo bolts and washers I don't think. Thanks for your reply
The all balls kits seem to be very hit and miss with people. It comes up on here often. Some people never have any luck with them at all.
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kwenske321
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kwenske321 6/29/2019 10:55pm
6/29/2019 10:55pm Edited Date/Time 6/29/2019 10:56pm
The same thing happened to me. I had my rear master cylinder coated and the site glass welded up. I was using an all balls rebuild kit when I put it back together. It would bleed up and then after a week just leak all over the clevis. When I took it apart it looked as if some of the coating overspray was inside the M/C. I took some red scotch brite and put it on the end of a dremel tool. This cleaned up the inside of the M/C where the piston/cup sit. I replaced all the parts with OEM Suzuki parts and it hasn’t leaked since. Hope this helps.
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