2019 kx450 rear brakes

Jbarros23
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Jbarros23
Edited Date/Time 7/2/2019 7:14am
We are having issues with the rear brakes locking up. First ride on the bike went through a set of pads, pads were bent. Took it to the dealer, they replaced rear caliper. Seemed to be fine then after a couple practices locked up again. Destroyed rotor and brake pads. Replaced rotor and pads. Today during the second moto last lap rear brake locked up. Could hardly spin the back wheel. I'm lost and frustrated. Any ideas
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Keith72
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Keith72 12/30/2018 7:19pm
12/30/2018 7:19pm
Have you checked the master cylinder?
Jbarros23
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Jbarros23 12/30/2018 7:21pm
12/30/2018 7:21pm
Keith72 wrote:
Have you checked the master cylinder?
Checked the fluid height. Seems good
Keith72
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Keith72 12/30/2018 7:32pm
12/30/2018 7:32pm
Keith72 wrote:
Have you checked the master cylinder?
Jbarros23 wrote:
Checked the fluid height. Seems good
It's not sticking? Pedal moves freely?

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Jbarros23
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Jbarros23 12/30/2018 7:36pm
12/30/2018 7:36pm
Keith72 wrote:
Have you checked the master cylinder?
Jbarros23 wrote:
Checked the fluid height. Seems good
Keith72 wrote:
It's not sticking? Pedal moves freely?
Have not checked that
mx317
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mx317 12/30/2018 7:51pm
12/30/2018 7:51pm
Lower your pedal. You may be dragging your brake.
Jbarros23
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Jbarros23 12/30/2018 7:58pm
12/30/2018 7:58pm
mx317 wrote:
Lower your pedal. You may be dragging your brake.
Yeah tried that. Was my first thought
Jbarros23
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Jbarros23 12/30/2018 8:01pm
12/30/2018 8:01pm
I've read the new 19 KX450F has a larger brake rotor, which makes it more sensitive. Almost thinking about buying a 18 set up
dancolvin633
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dancolvin633 12/30/2018 8:49pm
12/30/2018 8:49pm
Jbarros23 wrote:
I've read the new 19 KX450F has a larger brake rotor, which makes it more sensitive. Almost thinking about buying a 18 set up
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the 19
Jbarros23
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Jbarros23 12/30/2018 9:02pm
12/30/2018 9:02pm
Jbarros23 wrote:
I've read the new 19 KX450F has a larger brake rotor, which makes it more sensitive. Almost thinking about buying a 18 set up
dancolvin633 wrote:
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the...
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the 19
The people that switched, they having the same issues?? I'm going to take the brakes off the 250 and see if it works
dancolvin633
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dancolvin633 12/30/2018 9:31pm
12/30/2018 9:31pm
Jbarros23 wrote:
I've read the new 19 KX450F has a larger brake rotor, which makes it more sensitive. Almost thinking about buying a 18 set up
dancolvin633 wrote:
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the...
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the 19
Jbarros23 wrote:
The people that switched, they having the same issues?? I'm going to take the brakes off the 250 and see if it works
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake and the brake fluid is getting extremely hot and causing an issue? I know you said you adjusted the pedal?
Jbarros23
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Jbarros23 12/30/2018 9:37pm
12/30/2018 9:37pm
dancolvin633 wrote:
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the...
You need the rotor and the caliper mount and your good to go. A lot of people have went back to the smaller rotor on the 19
Jbarros23 wrote:
The people that switched, they having the same issues?? I'm going to take the brakes off the 250 and see if it works
dancolvin633 wrote:
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake...
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake and the brake fluid is getting extremely hot and causing an issue? I know you said you adjusted the pedal?
Yeah adjusted the brake pedal. It's my son's bike. He's an A rider, and doesn't have the same issue on his 250... im thinking since the brakes are so sensitive that it's over heating...
dancolvin633
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dancolvin633 12/30/2018 9:45pm
12/30/2018 9:45pm
Jbarros23 wrote:
The people that switched, they having the same issues?? I'm going to take the brakes off the 250 and see if it works
dancolvin633 wrote:
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake...
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake and the brake fluid is getting extremely hot and causing an issue? I know you said you adjusted the pedal?
Jbarros23 wrote:
Yeah adjusted the brake pedal. It's my son's bike. He's an A rider, and doesn't have the same issue on his 250... im thinking since the...
Yeah adjusted the brake pedal. It's my son's bike. He's an A rider, and doesn't have the same issue on his 250... im thinking since the brakes are so sensitive that it's over heating...
I’d bet my next paycheck that’s the issue. You can grind down the brake pads a bit. Put a chamfer on the braking edge. That will help a lottle but I’d suggest getting the smaller rotor
Paw Paw 271
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Paw Paw 271 12/31/2018 7:24am
12/31/2018 7:24am
Too much fluid in the master will also cause the break to drag.

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lawson34
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lawson34 2/6/2019 7:22pm
2/6/2019 7:22pm Edited Date/Time 2/6/2019 7:22pm
dancolvin633 wrote:
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake...
No not the same issue as your having. Most find the new rotor to be too touchy. I wonder if your not dragging the rear brake and the brake fluid is getting extremely hot and causing an issue? I know you said you adjusted the pedal?
Jbarros23 wrote:
Yeah adjusted the brake pedal. It's my son's bike. He's an A rider, and doesn't have the same issue on his 250... im thinking since the...
Yeah adjusted the brake pedal. It's my son's bike. He's an A rider, and doesn't have the same issue on his 250... im thinking since the brakes are so sensitive that it's over heating...
dancolvin633 wrote:
I’d bet my next paycheck that’s the issue. You can grind down the brake pads a bit. Put a chamfer on the braking edge. That will...
I’d bet my next paycheck that’s the issue. You can grind down the brake pads a bit. Put a chamfer on the braking edge. That will help a lottle but I’d suggest getting the smaller rotor
You can breathe on the rear pedal, and they lock up other than that brakes are fine on my end... Let's us know what the fix was
Chris Nichols 6/28/2019 10:29pm
6/28/2019 10:29pm
Has anyone had this before just went to change rear tyre and seen my disc is cracked in 4 different places?
Also does anyone know where I can get an aftermarket replacement for the 2019?
Chris Nichols 6/28/2019 10:29pm
6/28/2019 10:29pm
Chris Nichols wrote:
Has anyone had this before just went to change rear tyre and seen my disc is cracked in 4 different places? Also does anyone know where...
Has anyone had this before just went to change rear tyre and seen my disc is cracked in 4 different places?
Also does anyone know where I can get an aftermarket replacement for the 2019?

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dmm698
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dmm698 6/29/2019 5:39am
6/29/2019 5:39am
Chris Nichols wrote:
[img]https://p.vitalmx.com/photos/forums/2019/06/28/357163/s1200_BC2C159A_4165_45B3_A202_33CF3A299730.jpg[/img]

I have a brand new in package 19 kx450 pro x rear rotor sitting in my garage for my spare wheel, not installed yet. Haven’t gotten around to it. I believe you can only order directly through pro-x/wiseco, haven’t seen them posted anywhere else for sale.
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soggy 6/29/2019 9:38am
6/29/2019 9:38am
Jbarros23 wrote:
We are having issues with the rear brakes locking up. First ride on the bike went through a set of pads, pads were bent. Took it...
We are having issues with the rear brakes locking up. First ride on the bike went through a set of pads, pads were bent. Took it to the dealer, they replaced rear caliper. Seemed to be fine then after a couple practices locked up again. Destroyed rotor and brake pads. Replaced rotor and pads. Today during the second moto last lap rear brake locked up. Could hardly spin the back wheel. I'm lost and frustrated. Any ideas
have heard of alot of people going to steel braided rear line because the brake drags alot with stocker
DB97
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DB97 6/29/2019 4:47pm
6/29/2019 4:47pm
I just fixed the issue for good. Take off the heat shields on the pads not pushing evenly. Braided line helps too. Try heat shields takes 2 minutes.
dmm698
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dmm698 6/30/2019 5:24pm
6/30/2019 5:24pm
DB97 wrote:
I just fixed the issue for good. Take off the heat shields on the pads not pushing evenly. Braided line helps too. Try heat shields takes...
I just fixed the issue for good. Take off the heat shields on the pads not pushing evenly. Braided line helps too. Try heat shields takes 2 minutes.
I’ve had zero issues with my rear brake? B class moto. And I like the new front master so much I bought a new take off one off eBay and stuck it on my YZ 2 stroke.
AC133
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AC133 7/1/2019 5:24am
7/1/2019 5:24am
Are there any after market calipers or master cylinders?
Do people generally ride with their feet lilghtly resting on the brake pedal? I have a habit of doing that and that bit of friction completely fries my back brake on the 2019 kx 450. Other bikes seem to have more play before the back brake rubs.

My rotor was also cracked over the weekend. I bought a crappy one from the track shop and that got so hot the metal started to de-laminate. The caliper gets hot and the prongs that press the pads start to bend.

I have added braided lines and gone to the smaller brake rotor.
Also I am using either DP or oem pads.
Additionally I have lowered the pedal by grinding part of the screw at the bottom of the master cylinder.

Anyone found a solution to this yet except for riding with their feet up off the brake pedal which i find quite hard!
DB97
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DB97 7/1/2019 7:05am
7/1/2019 7:05am
Yeah take the heat shields off my rear wheel spins 2 revolutions now.
1
dmm698
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dmm698 7/2/2019 5:21am
7/2/2019 5:21am
AC133 wrote:
Are there any after market calipers or master cylinders? Do people generally ride with their feet lilghtly resting on the brake pedal? I have a habit...
Are there any after market calipers or master cylinders?
Do people generally ride with their feet lilghtly resting on the brake pedal? I have a habit of doing that and that bit of friction completely fries my back brake on the 2019 kx 450. Other bikes seem to have more play before the back brake rubs.

My rotor was also cracked over the weekend. I bought a crappy one from the track shop and that got so hot the metal started to de-laminate. The caliper gets hot and the prongs that press the pads start to bend.

I have added braided lines and gone to the smaller brake rotor.
Also I am using either DP or oem pads.
Additionally I have lowered the pedal by grinding part of the screw at the bottom of the master cylinder.

Anyone found a solution to this yet except for riding with their feet up off the brake pedal which i find quite hard!
Lower your brake pedal? I only rode my bike with the stock return spring one time, the other 9 hours or so on it have been with an adjustable spring like the one fast co offers.
DB97
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DB97 7/2/2019 5:24am
7/2/2019 5:24am
I don't think it's the pedal. Mine was dragging on the stand. Pulled heat shields off now it spins great.
AC133
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AC133 7/2/2019 5:29am
7/2/2019 5:29am
dmm698 wrote:
Lower your brake pedal? I only rode my bike with the stock return spring one time, the other 9 hours or so on it have been...
Lower your brake pedal? I only rode my bike with the stock return spring one time, the other 9 hours or so on it have been with an adjustable spring like the one fast co offers.
i have brake pads without the heat shields and it still has dragging.
I have been thinking to get a stronger return spring. Do you have a link to the spring please? Ill get one ordered.

Thanks,
DB97
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DB97 7/2/2019 5:31am
7/2/2019 5:31am Edited Date/Time 7/2/2019 5:32am
AC133 wrote:
i have brake pads without the heat shields and it still has dragging. I have been thinking to get a stronger return spring. Do you have...
i have brake pads without the heat shields and it still has dragging.
I have been thinking to get a stronger return spring. Do you have a link to the spring please? Ill get one ordered.

Thanks,
Hmm idk then only other thing is I have a braided line. Also Dubya told me to take the dust shields off rear spacers.
dmm698
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dmm698 7/2/2019 6:09am
7/2/2019 6:09am
AC133 wrote:
i have brake pads without the heat shields and it still has dragging. I have been thinking to get a stronger return spring. Do you have...
i have brake pads without the heat shields and it still has dragging.
I have been thinking to get a stronger return spring. Do you have a link to the spring please? Ill get one ordered.

Thanks,
https://www.worksconnection.com/p18061-brake-spring-return-kits

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