Hyosung GT250R No Brake Pressure With Calipers Off

[nick1408]

Ok, I took the rear calipers off as the brakes were sticky. Turned out it was all rusted up. I am about to put an order in for new calipers but decided to check the rest of the system before purchase. I pumped the brakes to see if I could get the fluid to come and make sure the master was good. No fluid came out. I blocked the end of the line to try and generate pressure but nothing. There is no resistance in the brake (understandable) but I would think that I should get fluid out when pumping the brakes.

Is this a correct assumption?

[onearmedbandit]

Very fair assumption, as your brakes are operated by hydraulic pressure. So yes, fluid should have come out. Time to check the master cylinder, oh and any possible damage to the brake line itself.

[DrunkenMistake]

Ok, I took the rear calipers off as the brakes were sticky. Turned out it was all rusted up. I am about to put an order in for new calipers but decided to check the rest of the system before purchase. I pumped the brakes to see if I could get the fluid to come and make sure the master was good. No fluid came out. I blocked the end of the line to try and generate pressure but nothing. There is no resistance in the brake (understandable) but I would think that I should get fluid out when pumping the brakes.

Is this a correct assumption?

Take the line off the master and pump it a few times, see if there is any fluid coming out of the master, if there is then there is probably air in the line somewhere and it just needs a really good bleed

[nick1408]

Lines are good (no leaks) so I will remove and check master. If there is no fluid it is shagged, hey?

[DrunkenMistake]

Lines are good (no leaks) so I will remove and check master. If there is no fluid it is shagged, hey?

Maybe, might be able to save it, would probably be easier to get a second hand one off the likes of an SV 650 or something similar im pretty sure the 250's have a 2pot rear brake as well, unless its the injected model

[nick1408]

I just took the line off the top of the master cylinder and no fluid came out when pumping the brake. I could see it sitting there but nothing came out. Looks like I need a new master as well as calipers.

[DrunkenMistake]

I just took the line off the top of the master cylinder and no fluid came out when pumping the brake. I could see it sitting there but nothing came out. Looks like I need a new master as well as calipers.


Just to make sure, you took the brake line off and not the line from the fluid pot?

[nick1408]

The funny thing is, the brake moves fine so I can't work out why the piston isn't moving?

[nick1408]

Just to make sure, you took the brake line off and not the line from the fluid pot?


No, brake line. I already had the line disconnected from the calipers.

[DrunkenMistake]

No, brake line. I already had the line disconnected from the calipers.

I made a post on Korider about my front master doing the same thing, it was poked, if you brought your bike from a dealer and you didnt buy it in 08, it should still be under factory warranty so long as you havnt voided it

[nick1408]

Thanks. I did buy it in 08 though from memory.

For the matter of $200 I can get the calipers and master and it should all be fixed.

[FJRider]

Lines are good (no leaks) so I will remove and check master. If there is no fluid it is shagged, hey?

No pressure often means no fluid. Brake levers can't pump what isn't there ...

Not shagged ... but needs work. Not always a major though.

As the brake pads wear ... brake fluid in the master cylinder drops. Often to the point where the piston is at its maximum travel ... if the fluid is not topped up, the piston does not move-and rusts up. Brake pressure is only causing the brake lines to expand and retract.

If the piston has gone past the seal ... it will need replaced. In some cases ... a good clean, flush with new fluid, refilled and bled ... and is good to go. (If you are lucky)

Beware ... brake fluid DOES NOT LIKE PAINT. Remove or well cover any painted item. You have been warned ... :laugh:

[nick1408]

Haha, cheers. I will keep the fluid away from the paint.

Thanks for the info on the master cylinder. I will take it apart when I pull it from the bike.

[Lelitu]

Beware ... brake fluid DOES NOT LIKE PAINT. Remove or well cover any painted item. You have been warned ... :laugh:

I always thought the problem was that it loves paint, for lunch.

[FJRider]

I always thought the problem was that it loves paint, for lunch.

As long as you understand the basic concept ... the two must not make contact with each other ... :psst:

[spanner spinner]

I use to work for a Hyosung dealership and the rear brake master cylinder is a problem. They will work for years happily on there normal stroke range but push them further that they normally move and they rip the seals to pieces. Use to see them all the time when a new tyre was put on when when the tyre fitters have pushed the pads back then tried to pump the brakes back up as the plunger moves further than it normally does. try bleeding the brakes with your fingers over the end of the brake line first just in case air has air locked the master cylinder as having your fingers over the end of the brake line gives the master cylinder something to work against but the fluid will force it's way past your fingers when it gets there. if you can't get any pressure it's time for a new master cylinder as Hyosung didn't sell a seal kit when I was working for them, might have changed now hopefully.

hope this helps