Fork bushings, when to replace?

Berni
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Berni
Edited Date/Time 12/8/2015 7:40am
I've got some wp open chamber forks in my Ktm exc. The forks in a short amount of time has gotten pretty harsh compared to what they used to be. I am going to change the oil this week, but I would like to know how do I detect that the bushings needs to be replaced? can the harshness be due to the bushings needing to be replaced?

I am currently running sae5 fork oil. Going to sae2.5 would be a big difference if I do not change the valving? I mostly ride enduro.


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moto455va
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moto455va 11/30/2015 11:19am
11/30/2015 11:19am
If you look at them and see the copper showing behind the teflon coating, then they need to be replaced. Although it wouldnt hurt to just replace them anyway since theyre not too expensive.
Berni
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Berni 11/30/2015 11:34am
11/30/2015 11:34am
Ok I will replace them anyways, but can be that they become harsh because of that? Or I should be looking for a different problem?

What about the change in viscosity, is it a big difference?
slipdog
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slipdog 11/30/2015 11:57am
11/30/2015 11:57am
Yes worn bushings will cause the forks to bind more as the move through the stroke. The tighter the tolerances between the tubes are, the smoother the up and down action will be.
slipdog
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slipdog 11/30/2015 12:00pm
11/30/2015 12:00pm
Also, when you service them check the base valve to make sure no debris has worked it's way into the valve body holding the shim stack open. That's an inherent issue with open bath forks and cause a funky feel as well.

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karlz
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karlz 12/1/2015 4:00am
12/1/2015 4:00am
Hi even if the Teflon coating looks good, they can still cause the forks to feel harsh. The thing to look for is how smooth the Teflon surface is. Also make sure the forks are running straight and the lower triple clamps are not over tight. When I say running straight I mean if the front wheel has been installed incorrectly the forks can get pulled together at the bottom.
slipdog
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slipdog 12/1/2015 5:00am
12/1/2015 5:00am
karlz wrote:
Hi even if the Teflon coating looks good, they can still cause the forks to feel harsh. The thing to look for is how smooth the...
Hi even if the Teflon coating looks good, they can still cause the forks to feel harsh. The thing to look for is how smooth the Teflon surface is. Also make sure the forks are running straight and the lower triple clamps are not over tight. When I say running straight I mean if the front wheel has been installed incorrectly the forks can get pulled together at the bottom.
Are you Karlace?
Berni
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Berni 12/1/2015 9:26am
12/1/2015 9:26am
Wheel is correcta and lower clamp almost loose. I am about ti start to dissasemble them and hopefully tomorrow thr bushings will be here. Let ser if its improves. I will por inside a mix od sae 5 and sae 2.5/ until now they had sae 5
Berni
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Berni 12/1/2015 11:03am
12/1/2015 11:03am
Ok I just took them apart and a nasty mud came out... that is the oil. Bushings do not look to bad but anyways I will replace them tomorow or the day after...

The oil had like 100 hours, maybe too much...
Berni
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Berni 12/8/2015 7:38am
12/8/2015 7:38am
Ok, I replaced the bushings, and keept the skf seals. Bushings seemed to be ok but anyways serie replaced.

Nos this forma serie revalved two years ago and they had almost no stiction. I really do not remember when they lost this plushness but since some time ago they have a lot of stiction. With the new bushings it was reduced just a little, then I gave some doble grease to the chrome tubes with a 1000 grit and some oil and seems to be somewhat verter, but estilo base more than desirabe stiction.

Any ideas about what could I do por check to eliminaré this stiction that the forma dos not used to have?
Berni
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Berni 12/8/2015 7:40am
12/8/2015 7:40am
My god... writing with the phone with the spanish autocorrect, sorry for the mistakesLaughing

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