YZ250 squishy front brake

blakegill57
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blakegill57
Edited Date/Time 10/3/2022 9:50am
I've got a 2016 YZ250 and I'm having some trouble getting the front brake dialed in. I'd like it to be fairly touchy and have a "like new" feeling. I already installed a new galfer rotor, stainless braided brake line, and new pro taper pads. Doing this didn't really change the feel in the lever. Still feels squishy and the rotor squeaks a bit. Do I need to rebuild the master cylinder? The caliper maybe? Any help is appreciated.
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jamiechapman418 3/29/2021 7:09pm
3/29/2021 7:09pm Edited Date/Time 3/29/2021 7:09pm
Zip tie the front brake on over night. Will work out any air bubbles if any
3
blakegill57
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blakegill57 3/29/2021 7:13pm
3/29/2021 7:13pm
jamiechapman418 wrote:
Zip tie the front brake on over night. Will work out any air bubbles if any
I gave that a try once, before I replaced the rotor, line, and pads and it didn't help much. I suppose I could give it another try. Do I need to loosen the reservoir cap to allow the air bubbles to be released or does that matter?
jamiechapman418 3/29/2021 7:23pm
3/29/2021 7:23pm
No can just zip tie. Maybe worth trying to suck the system out and add fluid and rebleed again too
Factor E
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Factor E 3/30/2021 1:24am
3/30/2021 1:24am Edited Date/Time 3/30/2021 1:24am
Bleed whole system down starting at master cylinder.
crack banjo fitting loose allowing fluid to release while holding lever in.
Then move to lower fitting do same.
now bleed using bleed screw.
Zip tie overnight
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419250f
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419250f 3/30/2021 5:34am
3/30/2021 5:34am
If that's the feel you want, don't bother. Just buy a used ktm master on ebay. That's what finally worked for me after throwing money at everything else first.
Skerby
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Skerby 3/30/2021 6:43am
3/30/2021 6:43am
I never won this battle with my YZ. Rebuilding the master was definitely not worth it.
Moto520
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Moto520 3/30/2021 8:00am
3/30/2021 8:00am
I can never get my brakes as tight as i want them......i would try a rebuild of the master cylinder with fresh everything and start over.
Rider 5280
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Rider 5280 3/30/2021 8:45am
3/30/2021 8:45am
I can sell you a CRF master cylinder I have laying around.
dmm698
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dmm698 3/30/2021 10:55am
3/30/2021 10:55am
be cautious of swapping other masters on.....

I really loved the lever profile and feel of my 19-21 KX450. I bought a 19-21 kx450 master + lever, and put it on my yz250. Yes , the lever is firm. Just like you are describing you want. But, it doesnt stop nearly as well. I believe it has a smaller bore, thus moving less fluid for the same master piston travel. I think if you're changing masters you should really pair the caliper with it.
blakegill57
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blakegill57 3/30/2021 11:59am
3/30/2021 11:59am
dmm698 wrote:
be cautious of swapping other masters on..... I really loved the lever profile and feel of my 19-21 KX450. I bought a 19-21 kx450 master +...
be cautious of swapping other masters on.....

I really loved the lever profile and feel of my 19-21 KX450. I bought a 19-21 kx450 master + lever, and put it on my yz250. Yes , the lever is firm. Just like you are describing you want. But, it doesnt stop nearly as well. I believe it has a smaller bore, thus moving less fluid for the same master piston travel. I think if you're changing masters you should really pair the caliper with it.
Yeah that is a good point to make. I will probably go ahead and re-bleed the system and go from there. I'll report back if I have any success.
rhummel628
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rhummel628 3/30/2021 7:16pm
3/30/2021 7:16pm
I had a squishy front on my 07 cr250. Ended up rebuilding the master and caliper and that fixed it. it wouldn’t bleed correctly no matter what I did before I rebuilt them.
Vet57
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Vet57 3/31/2021 4:16am
3/31/2021 4:16am
Rider 5280 wrote:
I can sell you a CRF master cylinder I have laying around.
What year?
timobijnen84 3/31/2021 7:04am
3/31/2021 7:04am
dmm698 wrote:
be cautious of swapping other masters on..... I really loved the lever profile and feel of my 19-21 KX450. I bought a 19-21 kx450 master +...
be cautious of swapping other masters on.....

I really loved the lever profile and feel of my 19-21 KX450. I bought a 19-21 kx450 master + lever, and put it on my yz250. Yes , the lever is firm. Just like you are describing you want. But, it doesnt stop nearly as well. I believe it has a smaller bore, thus moving less fluid for the same master piston travel. I think if you're changing masters you should really pair the caliper with it.
That is why a lot of people use crf masters on their yz. The diameter ratio of the is good.
FGR01
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FGR01 3/31/2021 7:15am
3/31/2021 7:15am
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip cracking the banjos, skip pushing from the bottom with a syringe, skip using a vacuum bleeder. Just take the caliper off and place it higher than the master cylinder. Use a bungee cord or something to tie it up to a shelf or hang it from the ceiling, whatever. Remove the pads so that you don't contaminate them with brake fluid and put a piece of plywood in there as a substitute. Make sure the bleed nipple is at the highest point and then just pump fluid up from the bottom using the lever/pedal. Since air naturally rises this is the simplest way to get a perfect bleed. This works especially well when the system is empty, like after swapping a hose.
6
murph783
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murph783 3/31/2021 9:18am
3/31/2021 9:18am
FGR01 wrote:
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip...
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip cracking the banjos, skip pushing from the bottom with a syringe, skip using a vacuum bleeder. Just take the caliper off and place it higher than the master cylinder. Use a bungee cord or something to tie it up to a shelf or hang it from the ceiling, whatever. Remove the pads so that you don't contaminate them with brake fluid and put a piece of plywood in there as a substitute. Make sure the bleed nipple is at the highest point and then just pump fluid up from the bottom using the lever/pedal. Since air naturally rises this is the simplest way to get a perfect bleed. This works especially well when the system is empty, like after swapping a hose.
Can’t believe I never thought to do that
blakegill57
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blakegill57 3/31/2021 9:51am
3/31/2021 9:51am
FGR01 wrote:
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip...
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip cracking the banjos, skip pushing from the bottom with a syringe, skip using a vacuum bleeder. Just take the caliper off and place it higher than the master cylinder. Use a bungee cord or something to tie it up to a shelf or hang it from the ceiling, whatever. Remove the pads so that you don't contaminate them with brake fluid and put a piece of plywood in there as a substitute. Make sure the bleed nipple is at the highest point and then just pump fluid up from the bottom using the lever/pedal. Since air naturally rises this is the simplest way to get a perfect bleed. This works especially well when the system is empty, like after swapping a hose.
murph783 wrote:
Can’t believe I never thought to do that
Yeah same here. That makes the most sense.
Paw Paw 271
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Paw Paw 271 3/31/2021 11:46am
3/31/2021 11:46am
Have you checked the run out on the new rotor. If this is not correct it will make the breaks feel weak. The break squeak tells me the rotor is not tracking true and this alters the pad contact under breaking.

Paw Paw
ianhendry46
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ianhendry46 4/3/2021 11:54pm
4/3/2021 11:54pm
I was having the same issue on my yz. I had a new KTM sitting there so I swapped the front Brembo master cylinder on to my bike. Man, what a huge difference. Easily the best thing I’ve done for my bike. OEM KTM master cylinders really aren’t that expensive and the lever profile is great.

Pit Row

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SoCalMX70
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SoCalMX70 4/4/2021 12:28am
4/4/2021 12:28am
CRF master on my 16 YZ was the trick. It made the biggest difference... More so than the ss line and 270mm rotor.
FGR01
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FGR01 9/29/2022 7:39am
9/29/2022 7:39am
FGR01 wrote:
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip...
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip cracking the banjos, skip pushing from the bottom with a syringe, skip using a vacuum bleeder. Just take the caliper off and place it higher than the master cylinder. Use a bungee cord or something to tie it up to a shelf or hang it from the ceiling, whatever. Remove the pads so that you don't contaminate them with brake fluid and put a piece of plywood in there as a substitute. Make sure the bleed nipple is at the highest point and then just pump fluid up from the bottom using the lever/pedal. Since air naturally rises this is the simplest way to get a perfect bleed. This works especially well when the system is empty, like after swapping a hose.
Coming back and just dropping this in there. As an alternative, I'll sometimes do it this way. Just did it again last night after rebuilding the master cylinder. Had a vacuum bleeder on the bottom, pulled a bunch of fluid through, system totally full but zero pressure. Put the master cylinder on the floor and within a few pumps of the lever and cracks of the bleeder it was rock solid. The vacuum bleeder on the nipple is not necessary, but allows you to keep the pads in and just keeps everything clean instead of having fluid all over the place.


1
Rider 5280
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Rider 5280 9/29/2022 9:15am
9/29/2022 9:15am Edited Date/Time 9/29/2022 12:31pm
FGR01 wrote:
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip...
As a side note, for anyone having brake probs. If you want to ensure it is 100% bled properly and eliminate that from the equation, skip cracking the banjos, skip pushing from the bottom with a syringe, skip using a vacuum bleeder. Just take the caliper off and place it higher than the master cylinder. Use a bungee cord or something to tie it up to a shelf or hang it from the ceiling, whatever. Remove the pads so that you don't contaminate them with brake fluid and put a piece of plywood in there as a substitute. Make sure the bleed nipple is at the highest point and then just pump fluid up from the bottom using the lever/pedal. Since air naturally rises this is the simplest way to get a perfect bleed. This works especially well when the system is empty, like after swapping a hose.
FGR01 wrote:
Coming back and just dropping this in there. As an alternative, I'll sometimes do it this way. Just did it again last night after rebuilding the...
Coming back and just dropping this in there. As an alternative, I'll sometimes do it this way. Just did it again last night after rebuilding the master cylinder. Had a vacuum bleeder on the bottom, pulled a bunch of fluid through, system totally full but zero pressure. Put the master cylinder on the floor and within a few pumps of the lever and cracks of the bleeder it was rock solid. The vacuum bleeder on the nipple is not necessary, but allows you to keep the pads in and just keeps everything clean instead of having fluid all over the place.


I needed this picture/write-up, as I've struggled multiple times to get Brembo master cylinders to bleed --- THANKS!

I also kept getting to the "system totally full but zero pressure" point and no further.

I've always been able to get Nissin masters to bleed quickly for some reason, but never Brembos (I've only tried 2 Brembo masters in full transparency --- wasn't successful with either, they are still in boxes and I replaced them with Nissins).
eric513anderson 10/2/2022 12:08pm
10/2/2022 12:08pm
SoCalMX70 wrote:
CRF master on my 16 YZ was the trick. It made the biggest difference... More so than the ss line and 270mm rotor.
What year/model crf master?
R VanKamp77
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R VanKamp77 10/3/2022 8:49am
10/3/2022 8:49am
SoCalMX70 wrote:
CRF master on my 16 YZ was the trick. It made the biggest difference... More so than the ss line and 270mm rotor.
eric513anderson wrote:
What year/model crf master?
Anything late model. The part number you want is: 45510-KRN-A91
2
SoCalMX70
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SoCalMX70 10/3/2022 9:50am
10/3/2022 9:50am Edited Date/Time 10/3/2022 9:51am
SoCalMX70 wrote:
CRF master on my 16 YZ was the trick. It made the biggest difference... More so than the ss line and 270mm rotor.
eric513anderson wrote:
What year/model crf master?
R VanKamp77 wrote:
Anything late model. The part number you want is: 45510-KRN-A91
What he said. I think mine came off a 2019, but the same part goes back quite a few years from what I recall.
1
eric513anderson 10/3/2022 6:44pm
10/3/2022 6:44pm
SoCalMX70 wrote:
CRF master on my 16 YZ was the trick. It made the biggest difference... More so than the ss line and 270mm rotor.
eric513anderson wrote:
What year/model crf master?
R VanKamp77 wrote:
Anything late model. The part number you want is: 45510-KRN-A91
Thanks!
1

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