Fork Oil - change frequency?

**zadok** · 13th December 2006, 08:22

How often is it recommended you change your fork oil? Is it a time or km traveled thing?
I am about to pick up an '03 Tiger which has done 35,000km. The bike is immaculate. The owner said that the next thing he was about to do to the bike if he kept it, was change the fork oil. Is it a priority or not.
He also said that he has had emulators fitted in the front forks to improve their performance. Never heard of them. Can anyone enlighten me please?

Big Dave - Is there anything about the Tiger I need to watch out for?

**What?** · 14th December 2006, 06:15

It's a distance thing - the oil is subjected to shear forces as it is forced through the valves, which degrade its performance.
My F650 maintenance schedule says to change fork oil every 20,000Km, which is what happens. Makes a difference, though not huge.

Gold Valve emulators are a fancy set of valves that go inside your forks. Supposed to emulate cartidges(?) - by all accounts they are worth the money.

**riffer** · 14th December 2006, 07:32

I change mine annually, or when I replace the oil seals. Likewise brake and clutch level fluid and antifreeze. Usually its a Xmas Holiday thing.

Two thing's for certain:

1. Changing fork oil will improve suspension performance
2. Changing fork oil without changing oil seals will cause said seals to fail.

**What?** · 15th December 2006, 06:07

Originally Posted by riffer

2. Changing fork oil without changing oil seals will cause said seals to fail.

Why?
My first F650 had the fork oil changed 7 times, never did the seals and never had a seal failure. Some other bikes I have owned had seal failure before the fork oil was ever changed.
I will agree, though, that if you separate the slider and staunchion, then fitting new seals on re-assembly is a damned fine idea.

**Flyingpony** · 15th December 2006, 07:45

How does one change their fork oil?
I can't see a "sump nut" on them. Got the feeling it's a bit more involved.

**McJim** · 15th December 2006, 08:00

Used to use oil/air suspension in the good ol' early days of mountain biking but changing fork oil and seals was just an arse. Some bright spark then came up with the idea of replacing the oil with elastomer. Basically a big cylinder of rubber which you could buy at different hardnesses.

This being New Zealand I can't wait to hear about all the reasons why this won't work on motorbikes! (Tall poppy syndrome)

**riffer** · 15th December 2006, 10:14

Originally Posted by Flyingpony

How does one change their fork oil?
I can't see a "sump nut" on them. Got the feeling it's a bit more involved.

Here's the simple way, for non-USD forks.

1. Remove the brakes calipers from the forks
2. Remove the front wheel from the forks
3. Remove the fork brace and fender from the forks
4. Slightly loosen the fork caps on the top of the forks
5. Undo the bolts on the top and bottom triple clamps and remove the clip-ons (if you have clip-ons - you may need to remove the top triples to get at the clip-ons)
6. Pull out the forks from the triples.
7. Undo the fork cap (You did remember to loosen it, didn't you?)
8. Curse like a sailor as the fork spring flies across the gargre as you finally get the top off the forks.
9. Hole the fork upside down and drain the old oil into a container. Leave the fork upside down for a good five minutes, then "pump" the fork up and down to remove the last of the oil.
10. For good measure leave the forks hanging upside down in the container to let the last of the oil out while you search the gargre trying to find the fork springs.
11. Carefully put the springs back in.
12. Pour the recommended amount of new fork oil back in.
13. Put the fork caps back on (may be a two man job to do this on some forks as one holds down the cap as the other spins the fork around). Do the caps up tight.
14. Reassembly is pretty much disassembly in reverse.

**Devil** · 15th December 2006, 12:47

Originally Posted by riffer

Here's the simple way, for non-USD forks.

1. Remove the brakes calipers from the forks
2. Remove the front wheel from the forks
3. Remove the fork brace and fender from the forks
4. Slightly loosen the fork caps on the top of the forks
5. Undo the bolts on the top and bottom triple clamps and remove the clip-ons (if you have clip-ons - you may need to remove the top triples to get at the clip-ons)
6. Pull out the forks from the triples.
7. Undo the fork cap (You did remember to loosen it, didn't you?)
8. Curse like a sailor as the fork spring flies across the gargre as you finally get the top off the forks.
9. Hole the fork upside down and drain the old oil into a container. Leave the fork upside down for a good five minutes, then "pump" the fork up and down to remove the last of the oil.
10. For good measure leave the forks hanging upside down in the container to let the last of the oil out while you search the gargre trying to find the fork springs.
11. Carefully put the springs back in.
12. Pour the recommended amount of new fork oil back in.
13. Put the fork caps back on (may be a two man job to do this on some forks as one holds down the cap as the other spins the fork around). Do the caps up tight.
14. Reassembly is pretty much disassembly in reverse.

Here's my steps. First step can be different depending on where your clip-ons are located, ie. above or below the top triple clamp. For the trumpy, its above the triple clamp.
With bike on rear stand:

1) Loosen clip-ons
2) Undo fork caps.
3) After placing suitable catch tray and rags around bottom of front wheel, open drain hole at bottom of forks. Allow to drain, pump forks if neccesary, measure fluid and compare with the amount that is supposed to be in there.
4) Do up drain hole and refill with appropriate level of fluid.
5) Do up fork caps
6) Tighten clip-ons.

Those bloody springs/spacers ffs. They sure do provide some entertainment when you go to put the cap back on!

**riffer** · 15th December 2006, 13:01

Originally Posted by Devil

3) After placing suitable catch tray and rags around bottom of front wheel, open drain hole at bottom of forks. Allow to drain, pump forks if neccesary, measure fluid and compare with the amount that is supposed to be in there.

There's a drain hole at the bottoms of the forks?
Bugger me, that would make it easier. I must look tonight when I do my seals.

**Devil** · 15th December 2006, 13:24

Originally Posted by riffer

There's a drain hole at the bottoms of the forks?
Bugger me, that would make it easier. I must look tonight when I do my seals.

hah, you're not the only one to make that comment!
I dont know if it's pretty specific bikes, but the ones i've had have had a drain-nut thingy. Not the adjuster/thingamy up the bottom of the fork though. If it's there, it'll be near the bottom of the fork on the side closest to the ground (ie, the side facing back toward the bike).

I'll see if I can find a pic.

**riffer** · 15th December 2006, 13:33

Just checked the manual Devil. No drain bolt. Must be a Trumpy thing.

I've got the do the seals so the forks are coming off anyway.

I got myself a great tool for putting the seals in at lunchtime though.

A bit of pipe, 420mm long, 45 inner dia, 50 outer dia. It'll be a great tool once I've smoothed it off with a half-round file.

Only $6 too...

**Devil** · 15th December 2006, 13:49

Here's some pics, the drain hole was also on my Old ZR250 kwaka.
Here is what you can do if you dont have those holes. You can still get it out the bottom without taking the forks off the bike.

http://www.vlc.com.au/~justin/about/..._bolt_undo.jpg

http://www.vlc.com.au/~justin/about/...aining_oil.jpg

**Devil** · 15th December 2006, 13:57

Just went out to my bike to look for you (turns out I dont have the drain on the triumph) but I just noticed fork oil leaking out the bottom of one of my forks! For fucks sake.