15 CRF250 susp. question

gharmon
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gharmon
Edited Date/Time 5/19/2016 2:19pm
Hey guys, exactly what is "blown" that causes this? My son had his suspension setup buy a local but he says he may not have the time to repair this by next weekend. He raced and qualified with his frontend jacked up like this all weekend.

The regional is next weekend (may 27-29). I haven't dove into any of these new air forks. I've replace fork seals and such on all the older versions so if I can repair this I might as well get it done.


So, what exactly is blown in this pic? Both bikes in the pic are 2015 CRF. The bike I'm referencing is the 471

PS. Before this weekend even started you could push down on the fork and upon rebound you could hear air coming from the top of the left fork. He said he landed on a downed rider and that's when the forks just collapsed like this.

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slipdog
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slipdog 5/17/2016 7:08pm
5/17/2016 7:08pm
Did he re set his air pressures? That would have to be a loss of pressure in the inner chamber and the balance chamber is now pulling the fork part of the way down into the stroke. Possibly a leak in the schrader valve?
Bruce372
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Bruce372 5/17/2016 8:29pm
5/17/2016 8:29pm
Check the o rings throughout the fork . It might be a quick fix after a trip to the hardware store
motosicko
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motosicko 5/17/2016 9:08pm
5/17/2016 9:08pm
So all weekend nobody at the track could help him get this resolved? I've been to a lot of races all over the US, but never to AL, must be some cut throat racing going down there if no one helped him out, and let him race like that.
Definitely a loss of air in the inner chamber. As slipdog stated check the Schrader on top of fork first. Release all the air pressure, then remove valve stem and replace it with a new one, to eliminate that as problem. Then pump it up to whatever air pressure he runs, and let it sit for a bit and re check pressure to make sure it holds. You can spray a little soapy water around fittings and fork seal area to see if and where it is leaking.
gharmon
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gharmon 5/18/2016 4:39am
5/18/2016 4:39am
We live in Alabama but the race was in North Georgia. There was one shop that offered to help fix it but they said they did not have the parts once they went back to their shop to look for them.
Thanks guys for the suggestions we will give it a try

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MxMobster471 5/18/2016 9:28am
5/18/2016 9:28am
The bike in question is mine. As far as trouble shooting at the track goes, it was very limited. As I'm not very familiar with the internal aspects of suspension as a whole. The pressure is usually between 175 to 180 in the top and 145 in the bottom. (Instructed to use these via setup guy) Upon checking after the get off with the downed rider we checked the pressure and it was down to 110 in the top and 135 in bottom. Reset it to normal settings on the stand after bleeding all release valves and pulled it off and dropped again and spike to 205 in too and bottom. Tried that same thing 2 to 3 times. That's about al we had time to do, I pulled up to last hate pick trying to get it diagnosed by the suspension vendor on hand.

If this seems like an easy fix to any of you then please enlighten me and my dad. A cost effective fix would be ideal for sure!

Thanks to all who responded thus far!
slipdog
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slipdog 5/18/2016 12:04pm
5/18/2016 12:04pm
MxMobster471 wrote:
The bike in question is mine. As far as trouble shooting at the track goes, it was very limited. As I'm not very familiar with the...
The bike in question is mine. As far as trouble shooting at the track goes, it was very limited. As I'm not very familiar with the internal aspects of suspension as a whole. The pressure is usually between 175 to 180 in the top and 145 in the bottom. (Instructed to use these via setup guy) Upon checking after the get off with the downed rider we checked the pressure and it was down to 110 in the top and 135 in bottom. Reset it to normal settings on the stand after bleeding all release valves and pulled it off and dropped again and spike to 205 in too and bottom. Tried that same thing 2 to 3 times. That's about al we had time to do, I pulled up to last hate pick trying to get it diagnosed by the suspension vendor on hand.

If this seems like an easy fix to any of you then please enlighten me and my dad. A cost effective fix would be ideal for sure!

Thanks to all who responded thus far!
Looks like your typing on a phone so just to be clear, you reset to 175 top and 135 bottom and the forks dropped immediately pulling it off the stand. Are you saying when it collapsed and you checked both pressures in the top and bottom chambers and they were 205?

I can't see any way that the pressure would go up in either one after setting them at a lower psi.

Did any oil come out of the valve on the bottom when you connected the gauge?

FWIW, you will always read 2-4psi lower in the upper and 7-9psi lower in the lower balance chamber when you re connect the gauge because you have to fill the line of the gauge to get a reading.
MxMobster471 5/18/2016 12:37pm
5/18/2016 12:37pm
slipdog wrote:
Looks like your typing on a phone so just to be clear, you reset to 175 top and 135 bottom and the forks dropped immediately pulling...
Looks like your typing on a phone so just to be clear, you reset to 175 top and 135 bottom and the forks dropped immediately pulling it off the stand. Are you saying when it collapsed and you checked both pressures in the top and bottom chambers and they were 205?

I can't see any way that the pressure would go up in either one after setting them at a lower psi.

Did any oil come out of the valve on the bottom when you connected the gauge?

FWIW, you will always read 2-4psi lower in the upper and 7-9psi lower in the lower balance chamber when you re connect the gauge because you have to fill the line of the gauge to get a reading.
My apologies if that was hard to understand.

I noticed the suspension after getting back to the truck from hitting the downed rider. The first time we checked the air pressure it was way low, somewhere around 110 in the top and 135 in bottom. I filled the forks back up to the suggested amount and took it off the stand. Pushed up and down on the forks a bit and then checked again. At this point it peaked (205).
motosicko
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motosicko 5/18/2016 1:09pm
5/18/2016 1:09pm
Something is way off if you are getting 205. Did the forks sag low like photo after you pumped them up from 110 lbs.? Are you using a quality digital suspension pump? Also shouldn't be more than 10 lbs difference between inner and balance pressure. How much do you weigh? Is the top of fork cap stock with 1 schrader fitting, or has someone added an additional fitting to air up the outer chamber, like the 16's have? Need to get back to the basics to be able to help out, but your story is a bit confusing.
slipdog
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slipdog 5/18/2016 1:21pm
5/18/2016 1:21pm
MxMobster471 wrote:
My apologies if that was hard to understand. I noticed the suspension after getting back to the truck from hitting the downed rider. The first time...
My apologies if that was hard to understand.

I noticed the suspension after getting back to the truck from hitting the downed rider. The first time we checked the air pressure it was way low, somewhere around 110 in the top and 135 in bottom. I filled the forks back up to the suggested amount and took it off the stand. Pushed up and down on the forks a bit and then checked again. At this point it peaked (205).
If you checked the pressure while the bike was on the ground and the forks compressed a bit the top chamber pressure could rise since the air space would be smaller in the cartridge. If you put it back on the stand to check the pressure, I'm at a loss as to how it could rise 20psi like that.
MxMobster471 5/18/2016 1:33pm
5/18/2016 1:33pm
Crashed.
Went back to the truck, noticed suspension was sagging pretty bad.
Put it on the stand, read 110 in the top and 135 in the bottom (Works connection pump)
Filled chambers up to speculation.
Pulled it off the stand and compressed the front end a few times.
Put it back on the stand, checked it. Read 205.
The front end would sit fine but after compressing it a few times it would no longer return to the top of the stroke.
As far as aftermarket things go, it has an after market bleeder on the right fork and they guy who did my suspension put a Schrader valve in place of the old bleed cap on the left fork as well. The Schrader valve affiliated with filling up the out chamber is stock.

I weigh about 165 with gear and race in the C (novice) class.
motosicko
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motosicko 5/18/2016 2:11pm
5/18/2016 2:11pm Edited Date/Time 5/18/2016 2:31pm
Ok. That's cleared up now.
I'm about the same with gear. I run 165 inner, 0 outer, 162 balance. Try setting your balance no more than 10 lbs less than inner. You do know that the balance air fills in bottom of fork I hope. The fitting that was added(right side on left fork cap) is the outer spring pressure, shouldn't need any more than 5 lbs there. Less air in the balance will let the fork ride higher in the stroke.
motosicko
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motosicko 5/18/2016 2:41pm
5/18/2016 2:41pm Edited Date/Time 5/18/2016 9:14pm
I would check over the fork tubes really good too. May have dented or ovalled upper fork tube just enough to keep bushings from moving smoothly.
The more I read into this I'm beginning to think you may have bent an upper fork tube. I'd remove the forks and make sure each side is moving free throughout the stroke.
garagedog 5/18/2016 7:02pm
5/18/2016 7:02pm
This is my favorite line... "Filled chambers up to speculation."

(following this thread, hope to get the same bike soon)
MxMobster471 5/19/2016 10:43am
5/19/2016 10:43am
Yeah, I would stay tuned. My dad got the bike to my suspension guy and he cleaned all the schraders and said it was holding up fine. The plan was to bring the bike to my work today at lunch. Got a text saying "something is wrong with bottom pressure" no other information at this point but will update as soon as I hear something back.
gharmon
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gharmon 5/19/2016 12:35pm
5/19/2016 12:35pm
Quote from susp guy: "The inner rod was kinked at an angle but when I got it apart to it, it straightened out and that's why it wasn't doing anything wrong which confused me. Once the bike moves, it leaks because of the damaged cartridge seal housing"

Is that making any sense? The suspension guy totally took his own personal bikes fork internals and put in mine so I can make it out to a race this weekend. Kudos to him.
MxMobster471 5/19/2016 2:19pm
5/19/2016 2:19pm
Just for the record pops, it's my bike... Lol

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