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TOPIC: Change of front fork oil

Change of front fork oil 2 years 10 months ago #90748

  • LeonL
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How often do you need to change the fork oil? I had Wilber Progressive springs fitted at approximately 30 000 km the bike now has 73000 on the clock. Does rider weight have anything to do with the viscosity of the oil that you use? I see at Kawa they have light oil etc.
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Change of front fork oil 2 years 10 months ago #90752

  • Abre
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I think it is due for a change.
Abré le Roux
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Last Edit: 2 years 10 months ago by Abre.
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Change of front fork oil 2 years 10 months ago #90755

  • Psycho Porra
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I agree with Abre on that, change your oil.
I use a 5weight oil in my shocks but Wookie here on the forum is the shock guru so you can ask him
"The Brave do not Live Forever, but the Cautious do not Live at all"
Last Edit: 2 years 10 months ago by Psycho Porra.
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Change of front fork oil 2 years 10 months ago #90758

  • Piet
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Fork oil every 15 000km. And you will feel a massive difference! I don't even want to know what your forks feel like after 43000km! :laugh:

Stock oil viscosity for the KLR is 10W, and I have stuck to that with good results!

The oil viscosity determines damping, which is in layman's terms "how fast the forks are allowed to compress and extend again". The amount of force the suspension can resist is determined by your spring constant (load per mm compression), so the springs are directly related to rider weight. Damping is also affected by rider weight, but to a lesser extent (think hitting a few big holes in succession - damping can help resist bottoming out).
Last Edit: 2 years 10 months ago by Piet.
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Change of front fork oil 2 years 10 months ago #90768

  • Wookie
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LeonL...

If you have the standard damper rod forks fitted you should be changing the fork oil every 6 months to 1 year depending on how often and how hard the bike is ridden. The way these forks work is by forcing the oil through holes in the damper rod and this breaks the oil chains down quite quickly.

ATF is perfect oil to use... both cheap and good anti-foaming properties.

Changing the oil is a fairly simple job and in both the 38mm and 41mm forks.
The 38mm forks can be drained on the bike but the 41mm must be removed from the bike.
In both cases I have found it easier to drain and flush the forks once they are off the bike.

Cheers

W
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Change of front fork oil 2 years 10 months ago #90776

  • Shadow
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I recently changed the oil on my bike, used Motul, but clearly I left it far too long after reading these comments - the forks were knocking when I hit a speed bump, the new oil sorted that out nicely (I also have Wilbers fitted) - will change more frequently from now on :unsure:
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Change of front fork oil 2 years 10 months ago #90779

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Just a cautionary note regarding fork oil weight.

At very low viscosity numbers the standard testing methods do not give consistant results making the quoted SAE or weight numbers almost meaningless in comparing one manufacturers oil to another.
One manufactirers 5wt could equal anothers 10wt in actual viscosity.

If you are going to try out different oil weights then rather stick to one manufacturers oil when you do. This way you can use oils based on a relative scale.

Just FYI... ATF has a viscosity of aboutr 7.5wt to 10wt
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Change of front fork oil 2 years 7 months ago #93386

  • Darknight
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I am just reviving this topic again,

How easy is it to change the fork oil yourself on a new shape?
#The Dark Knight

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Change of front fork oil 2 years 7 months ago #93387

  • Ryderod
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How technically adept are you? If you can tinker around on basic maintenance procedures then it is not too difficult, if you don't really work on your bike, it could be challenging.
Also, are you just doing an oil change? That is a lot easier, loosen top clamp bolts, loosen top fork cap,remove forks, remove cap & spring, turn upside down, stroke a good few times to work out all the oil, leave upside down overnight. Flush with atf, add correct oil and close up and fit back.
My thinking is if one has gone as far as removing the forks to change the oil, especially if after a lengthy period, might as well change the seals at the same time. Nothing worse than putting in fresh oil and a few months down the line a seal fails!
There's also the added benefit of being able to really clean all the components nicely.
This does require a bit more stripping plus a few more specialized tools though which are easy enough to make, 24A/F nut welded onto a pipe, or 2 nuts locked onto some threaded rod for the damping rod, and some pvc piping for seal drivers.
Some basic things to usually watch out for are (1) ensuring seal faces the correct way, (2) to fit seal first place something like a small plastic bag with lots of grease over the start of the stanchion tube to prevent damaging the seal lip on the sharp face, (3) if you don't have a proper seal driver and use pvc, take your time, make sure you have the pipe resting on the outer hard part of the seal when tapping it in, not near the sealing edge, a rubber mallet is better than a hammer to tap with in case you bump the rod (4) correct oil quantity, or air gap is important, the syringe with stainless rod and collar kit from Startline is perfect for this, (5) make sure the top cap is threaded on a good distance by hand to avoid cross threading the fine pitch.
Try googling a few YouTube clips first so you have an idea, if you've done it once you'll see how easy it is.



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Last Edit: 2 years 7 months ago by Ryderod.
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Change of front fork oil 2 years 7 months ago #93388

  • Darknight
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I am quite comfortable around the bike and taking things apart. So removing the forks should'nt be an issue. I just want to be sure of the correct way to remove them. And I do have to tools for it. As for stripping them completely, I do not have the tools for that. I will how ever replace the oil and change the seals while I am at it.
What weight of oil do you suggest?

Many thanks!
#The Dark Knight

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