2024 Kawasaki KX450 and KX450X

2/23/2026 9:23am
motoxxx599 wrote:
Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a...

Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a race a week ago the rear brake locked up solid. It stayed locked up for about 15 minutes and finally let loose. I bled the system and replaced the oil with DOT 5 oil. I checked to make sure the rotor wasn't bent. Yesterday I rode the bike and it happened again almost right away. I got the bike back to the truck and opened the bleed screw and the brake freed up right away. Im not a brake dragger and yesterday I was really conscience of my boot position but it happened a couple of times yesterday within 10 minutes of riding so I parked it. Any ideas?

Probably the caliper seizing. You can probably find a cheap used one on mx locker or rebuild the one you have. 

1
chasetwo79
Posts
1562
Joined
12/1/2019
Location
Truckee, CA, CA US
2/23/2026 9:44am

140 hours

chasetwo79 wrote:

Have you rebuilt it in any capacity? Top and or bottom end? 

Not yet. I was going to do it this summer when it got hot. Might have stretched her too far. I did a piston at 120...

Not yet. I was going to do it this summer when it got hot. Might have stretched her too far. I did a piston at 120 hours on my 19 kx450 and it looks great so I figured I’d stretch this one a bit longer. Only thing I’ve done to her is clutches and she has been great up to this point. 

I'd just do like you said, buy a new one and then rebuild the old one for a backup/practice bike. Resell value isn't great right now on them. More fun to keep. 

FGR01
Posts
5993
Joined
10/1/2006
Location
AZ US
Fantasy
2/23/2026 3:54pm
motoxxx599 wrote:
Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a...

Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a race a week ago the rear brake locked up solid. It stayed locked up for about 15 minutes and finally let loose. I bled the system and replaced the oil with DOT 5 oil. I checked to make sure the rotor wasn't bent. Yesterday I rode the bike and it happened again almost right away. I got the bike back to the truck and opened the bleed screw and the brake freed up right away. Im not a brake dragger and yesterday I was really conscience of my boot position but it happened a couple of times yesterday within 10 minutes of riding so I parked it. Any ideas?

Possibly overfilled. Try setting the level only about 3/4 way up the sight glass.

2
MXer391
Posts
416
Joined
2/10/2014
Location
Altoona, PA US
2/24/2026 7:14am

Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer and always blew the bike off with compressed air afterwards. They were fine the last ride in the fall and went to move it recently and they're notchy. I'm pretty disappointed. 

The Shop

Sandusky26
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3385
Joined
7/28/2021
Location
Eastern, NC US
2/24/2026 7:16am

I think he’s talking about a problem he elaborated on way earlier in this thread.

Sandusky26 wrote:
I don't remember posting about problems in this thread, you might be thinking about my 22.My 24 started making a noise from the bottom end on...

I don't remember posting about problems in this thread, you might be thinking about my 22.

My 24 started making a noise from the bottom end on the clutch side. Sounds like a loose header type of noise, header and everything is tight. I think the bottom end is going out, time for a rebuild.

You might be right.  You’re hard on equipment!

It seems that way. OEM crank is 500$, what do you guys think about using a Pro-X rod kit?

My clutch basket is pretty notched, I'm going to take some pics and see what you guys think. I don't want to file it, and it feels fine at the lever.

2/24/2026 7:34am
MXer391 wrote:
Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer...

Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer and always blew the bike off with compressed air afterwards. They were fine the last ride in the fall and went to move it recently and they're notchy. I'm pretty disappointed. 

If you like it pretty snug it will go bad in 30 hours for sure. 

3
Timo
Posts
1391
Joined
1/9/2021
Location
Wichita, KS US
2/24/2026 7:39am
motoxxx599 wrote:
Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a...

Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a race a week ago the rear brake locked up solid. It stayed locked up for about 15 minutes and finally let loose. I bled the system and replaced the oil with DOT 5 oil. I checked to make sure the rotor wasn't bent. Yesterday I rode the bike and it happened again almost right away. I got the bike back to the truck and opened the bleed screw and the brake freed up right away. Im not a brake dragger and yesterday I was really conscience of my boot position but it happened a couple of times yesterday within 10 minutes of riding so I parked it. Any ideas?

FGR01 wrote:

Possibly overfilled. Try setting the level only about 3/4 way up the sight glass.

Is DOT 5 okay with the nissin system? Most are DOT 4, dot 5 is silicone based and can swell the seals.

MXer391
Posts
416
Joined
2/10/2014
Location
Altoona, PA US
2/24/2026 8:13am
MXer391 wrote:
Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer...

Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer and always blew the bike off with compressed air afterwards. They were fine the last ride in the fall and went to move it recently and they're notchy. I'm pretty disappointed. 

If you like it pretty snug it will go bad in 30 hours for sure. 

I have them a little on the tight side. Are you replacing with OEM or is there a better option?

Sideways91
Posts
133
Joined
8/15/2022
Location
Dayton, NV US
2/24/2026 8:40am

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

2
2/24/2026 8:43am
MXer391 wrote:
Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer...

Steering stem bearing took a sh*t on my bike at 30 hours. I greased them really well when new. Was very careful with the power washer and always blew the bike off with compressed air afterwards. They were fine the last ride in the fall and went to move it recently and they're notchy. I'm pretty disappointed. 

If you like it pretty snug it will go bad in 30 hours for sure. 

MXer391 wrote:

I have them a little on the tight side. Are you replacing with OEM or is there a better option?

I have had the most luck with oem. Anyone else had luck with aftermarket?

1
mx4all
Posts
264
Joined
4/16/2017
Location
SE
2/24/2026 11:03am
motoxxx599 wrote:
Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a...

Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a race a week ago the rear brake locked up solid. It stayed locked up for about 15 minutes and finally let loose. I bled the system and replaced the oil with DOT 5 oil. I checked to make sure the rotor wasn't bent. Yesterday I rode the bike and it happened again almost right away. I got the bike back to the truck and opened the bleed screw and the brake freed up right away. Im not a brake dragger and yesterday I was really conscience of my boot position but it happened a couple of times yesterday within 10 minutes of riding so I parked it. Any ideas?

Dot 5 is silicone based and will make the seals swell and might increase the pressure in the system and therefore lock the brake. 

Use dot 4 or 5.1. 5.1 got higher boiling point. 

2
crmx105
Posts
615
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Location
Dunnellon, FL US
2/24/2026 2:48pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

FGR01
Posts
5993
Joined
10/1/2006
Location
AZ US
Fantasy
2/24/2026 5:11pm
motoxxx599 wrote:
Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a...

Im having rear brake issues on my 25 SR. This bike has 7 hours on it. In the second moto on the second lap of a race a week ago the rear brake locked up solid. It stayed locked up for about 15 minutes and finally let loose. I bled the system and replaced the oil with DOT 5 oil. I checked to make sure the rotor wasn't bent. Yesterday I rode the bike and it happened again almost right away. I got the bike back to the truck and opened the bleed screw and the brake freed up right away. Im not a brake dragger and yesterday I was really conscience of my boot position but it happened a couple of times yesterday within 10 minutes of riding so I parked it. Any ideas?

mx4all wrote:
Dot 5 is silicone based and will make the seals swell and might increase the pressure in the system and therefore lock the brake. Use dot 4...

Dot 5 is silicone based and will make the seals swell and might increase the pressure in the system and therefore lock the brake. 

Use dot 4 or 5.1. 5.1 got higher boiling point. 

This.  I skipped right over the part in the original post about using DOT-5.  Definitely a no-no.

Shawnh
Posts
54
Joined
12/18/2018
Location
Brighton, CO US
2/24/2026 5:58pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

I just pulled mine and it looked perfect. I don't grease the seal but there is no sign of leakage, it actually seems to fit really tightly. I really like the setup.

1
Sideways91
Posts
133
Joined
8/15/2022
Location
Dayton, NV US
2/24/2026 6:20pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

Shawnh wrote:
I just pulled mine and it looked perfect. I don't grease the seal but there is no sign of leakage, it actually seems to fit really...

I just pulled mine and it looked perfect. I don't grease the seal but there is no sign of leakage, it actually seems to fit really tightly. I really like the setup.

Mine appears to fit tight as well and after a relatively wet desert race I don't see any signs of dirt ingestion in the air boot. Only reason I noticed it was because I greased the seal to be sure as I had no way to physically feel around the sealing area like I would typically on euro bikes, and upon removing the filter noticed a 3-4" section with grease undisturbed. With the filter off a .010" feeler gauge easily fits between the seal and airbox. In a silty race this would be a huge issue. 

Shawnh
Posts
54
Joined
12/18/2018
Location
Brighton, CO US
2/24/2026 6:27pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

Shawnh wrote:
I just pulled mine and it looked perfect. I don't grease the seal but there is no sign of leakage, it actually seems to fit really...

I just pulled mine and it looked perfect. I don't grease the seal but there is no sign of leakage, it actually seems to fit really tightly. I really like the setup.

Sideways91 wrote:
Mine appears to fit tight as well and after a relatively wet desert race I don't see any signs of dirt ingestion in the air boot...

Mine appears to fit tight as well and after a relatively wet desert race I don't see any signs of dirt ingestion in the air boot. Only reason I noticed it was because I greased the seal to be sure as I had no way to physically feel around the sealing area like I would typically on euro bikes, and upon removing the filter noticed a 3-4" section with grease undisturbed. With the filter off a .010" feeler gauge easily fits between the seal and airbox. In a silty race this would be a huge issue. 

I'll grease mine before riding this weekend and see if I see any issues. Could yours be warped? Where is the spot that isn't sealing?

Sideways91
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133
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Location
Dayton, NV US
2/24/2026 7:14pm
IMG 8883.jpeg?VersionId=op.7ZyDeIMG 8907 3.jpeg?VersionId=eTXnGijus tr1LaXBdMWgCjLH08YD9
JB500
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324
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Location
Granger, IN US
2/25/2026 6:03pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

crmx105 wrote:

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

crmx105
Posts
615
Joined
5/7/2016
Location
Dunnellon, FL US
2/25/2026 9:44pm
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

crmx105 wrote:

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

JB500 wrote:
I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change...

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

Yep I tried the Pro seal today with the Tusk and had the same result. 

Leemur891
Posts
387
Joined
5/12/2022
Location
Fort Collins, CO US
Fantasy
2/27/2026 5:24pm

Picked up v1 of the full yosh system for a smoking deal and got it installed today. I’ve been running the gutted stock can since I purchased the bike. I know everyone has their opinions on exhausts, but man, I feel like I’ve been riding a restricted bike this entire time until now. Stoked with the upgrade.

4
Mx286
Posts
488
Joined
9/5/2011
Location
Owensboro, KY US
2/28/2026 4:53am
Sideways91 wrote:
Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about...

Anyone that uses the Tusk Quick Air setup, put grease on the seal, mount it, then pull it out and review the grease, mine has about a .010" gap in the front bottom portion where it is not making contact with the airbox. 

crmx105 wrote:

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

JB500 wrote:
I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change...

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside not letting it go into place.

Shawnh
Posts
54
Joined
12/18/2018
Location
Brighton, CO US
2/28/2026 6:32am
crmx105 wrote:

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

JB500 wrote:
I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change...

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

Mx286 wrote:
Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside...

Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside not letting it go into place.

Mine fits very tight as well and takes a bit of a push to get the pins in the holes.  It is definitely a much tighter fit than the stock cage and I do have to fiddle with it to get it all the way in but to me, this is a good thing and helps to make it fit tighter against the rubber seal.  

crmx105
Posts
615
Joined
5/7/2016
Location
Dunnellon, FL US
2/28/2026 7:26am
crmx105 wrote:

I am running one and haven't checked it but have not seen a signs of dirt/dust getting by. Imagine Pro-seal might solve that?

 

JB500 wrote:
I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change...

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

Mx286 wrote:
Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside...

Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside not letting it go into place.

Found that if you move the Tusk filter assembly up and down it helps getting it seated all the way if that makes sense?

JB500
Posts
324
Joined
7/14/2018
Location
Granger, IN US
2/28/2026 11:52am
JB500 wrote:
I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change...

I run the filter set up too and am a clean filter freak. I do not grease mine, but I clean the surfaces each filter change, which is one practice day or one race day. Intake has remained clean and seal surfaces are clean. I do only have 27 hours on the bike and filter set up. 
I did attempt to use the pro seal when I got the filter kit, and it was to tight to fit the Tusk kit into the slider tabs with the pro seal installed. 

Mx286 wrote:
Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside...

Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside not letting it go into place.

crmx105 wrote:

Found that if you move the Tusk filter assembly up and down it helps getting it seated all the way if that makes sense?

I don’t have issues with it lining up, but agree with crmx here, you do have to put it in relatively flat to the mating surface on the air box to get the cage into the OEM tabs on the far side of the air box. That slight movement up and down to seat the cage under the tabs is what I think he’s referring to. 
I get my cage in with filter complete, then after latching, I use my hand with thin rubber gloves to reach in and ensure everything is in its place under the tabs. I do this with any air filter change, but this air box is just impossible to see into. 

crmx105
Posts
615
Joined
5/7/2016
Location
Dunnellon, FL US
2/28/2026 6:04pm
Mx286 wrote:
Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside...

Did you guys have issues when first installing? Mine doesn’t line up properly. Seems it’s just a tick off and hits the plastic on the backside not letting it go into place.

crmx105 wrote:

Found that if you move the Tusk filter assembly up and down it helps getting it seated all the way if that makes sense?

JB500 wrote:
I don’t have issues with it lining up, but agree with crmx here, you do have to put it in relatively flat to the mating surface...

I don’t have issues with it lining up, but agree with crmx here, you do have to put it in relatively flat to the mating surface on the air box to get the cage into the OEM tabs on the far side of the air box. That slight movement up and down to seat the cage under the tabs is what I think he’s referring to. 
I get my cage in with filter complete, then after latching, I use my hand with thin rubber gloves to reach in and ensure everything is in its place under the tabs. I do this with any air filter change, but this air box is just impossible to see into. 

Yes. There are holes on the back side of the air box that the base plate lock's into. The Tusk base plate is a much tighter fit so when you move it up and down it locks one corner in at a time which makes it easier. The holes are on the end of the track that the filter assy slides into, not to be confused with the holes where you clip the assy in.

Sideways91
Posts
133
Joined
8/15/2022
Location
Dayton, NV US
2/28/2026 7:25pm

RMATV sent me a replacement cage and still have a .010" gap between the seal and the airbox.

1
Sideways91
Posts
133
Joined
8/15/2022
Location
Dayton, NV US
3/4/2026 10:24am

FYI, Rockymountain/Tusk have been great to work with and have currently pulled the filter assembly from their site while they review this issue.

3
Leemur891
Posts
387
Joined
5/12/2022
Location
Fort Collins, CO US
Fantasy
3/4/2026 5:43pm

Is the 25/26 ecu plug and play with the 2024?

crmx105
Posts
615
Joined
5/7/2016
Location
Dunnellon, FL US
3/4/2026 6:04pm
Sideways91 wrote:

FYI, Rockymountain/Tusk have been great to work with and have currently pulled the filter assembly from their site while they review this issue.

If they put a thicker gasket on the filter base plate it should solve the issue?

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