Changing fork oil - remove forks?

[bombjack]

I'm about to change the oil in the forks. The service manual says that I have to remove the forks first. Is that really necessary?
Can't I just remove the front wheel and drain the old oil, then remove the top fork bolts and add new oil?

[The Buddha]

There is no drain on a GS fork. Katana forks 89-96 do ...
Cool.
Buddha.

[DoD#i]

It's not that hard, really, and yes you have to do it if you are going to do anything like a proper job.

Hint - you will generally have more fork oil than you need. Rather than leaving a significant (but not enough to do a second set of forks) amount over, use most of the excess (by precalculation) to flush the forks between your initial drain, and the fill. ie, if you need 387 ml per side, and you have 1000 ml, you've got 113ml extra per side. after draining the old oil, put 80-100 ml per side in and pump the forks to work it all around with the traces of remaining oil oil, then drain it out before putting in your 387 ml. Helps to get out more of the old crud.

[bombjack]

OK, thanx. I guess I have no way around taking of the forks then.
DoD#i , Thanx for the hint. I'll buy one liter of fork oil then! 

[coll0412]

I wouldn't worry about "flushing" the forks. Unlike cartridge forks and modern forks with shims stacks to control damping where particles in the fork oil effect the shim stack, there is really nothing to worry about like this for the GS. You do want to get the old oil out and any suspended material out of there.

To do this you need to take the forks off the bike, invert them, and pump them like..umm..well something not appropriate.


Taking the forks off is actually pretty easy if you have a centerstand still attached. Basically you need put it on the center stand, put a weight on the back of the bike that is sufficient to pick the front end up. Remove wheel, remove brake caliper, front fender and fender bracket, and then remove the forks.

Just a tip, remove the springs while the forks are still in the triple clamps to make it much easier as you don't need to hold the forks in a vice with a rag on them.

[The Buddha]

Get a long stiff hose and drop it  in the fork leg to the bottom. Then suck it out with a vacuum pump.
That should get it empty.
However its not like engine oil that has to be changed every 3K ...
Cool.
Buddha.

[RichDesmond]

It's best to take the forks off. That's the only way to get all the old oil out. The suction method always leaves some, and the part it leaves is the dirtiest, nastiest bit. If you need directions on the procedure look here:

http://www.sonicsprings.com/catalog/damper_rod_forks_tech_article.php

Just ignore the part about the springs and spacer if you're putting the stock springs back in.

[JB848]

I really need to do this on my 1990. I am sure that I could just do it but I sure would like to see some detailed pictures of some one doing it first that I could follow.

Robert

[Bluehaze]

hints: Do the forks one at a time.  And loosen just loosen the fork caps first ... before removing each fork.

[black and silver twin]

Get a long stiff hose and drop it  in the fork leg to the bottom. Then suck it out with a vacuum pump.
That should get it empty.
However its not like engine oil that has to be changed every 3K ...
Cool.
Buddha.

that's what i did and it works great, no it doesn't get ALL the oil and ALL the crud out but 95-99% seems fine for forks.

P.S. consider upgrading to 15 or 20 weight oil, stock is 10 weight and way too soft.

[JB848]

OK I guess I have to be specific. Some one please....when you do a fork rebuild, maintenance, take pictures and post them.

In this economy I can't afford to make a mistake. Some one that knows show us with pictures how?

[ineedanap]

For a full rebuild, the kat write up in the FAQ is identical to the steps for the GS and it has pictures too.  

If you're just doing an oil change, here's a step by step.  Seriously it's easy.  You really can't mess it up and there's really nothing to take a picture of.  

1.  Put bike on center stand.
2.  Find a 2x4 and cut it to the right length to jam between floor and engine mount to hold front up.  Alternatively, you can put a bunch of weight on the tail of the bike to lift the front end up as well.
3a. 1989 or bikes with clipons.  Loosen (only a turn or so) but don't remove fork cap.  It's a 1/2 inch rachet square under the rubber cap.
3b. 1990-2008.  Remove 4 handlebar clamp bolts.  Frig about with the handlebar to keep it from dangling awkwardly by the control cables.  Then do 3a.
4.  Remove cotter pin for axle
5.  Remove brake caliper bolts.  
6.  Remove axle.
7.  Remove wheel.
8.  Remove 10mm bolts holding brake line to fork and speedo cable to fork.
9.  Remove fork brace (4 big allen head bolts and 4 small allen heads with nuts under fender for fender.  It's easier to turn the 4 nuts, not the allen wrench.  Don't loose the 4 washers.  
10.  Remove fender
11. Loosen but don't remove upper and lower fork bolts while holding fork.  Fork will slide out bottom.
12. Finish removing fork cap.  Push down while unscrewing because it has some spring pressure.
13. Turn fork upside down.  Spacer, fork spring and washer will fall out with oil.  
14.  Add a little fresh oil and compress/extend forks to flush them clean.
15.  Dump that out.
16.  Add 387ml of new oil.
17.  Drink a beer.
18.  Install in order...spring, washer, spacer
19.  Screw cap back on.
20.  Repeat 11-19 for other fork.
21.  Installation is reverse of removal.  Tighten everything to torque specs.  They're listed here somewhere.  Don't forget #3 both on removal and installation.

Sorry, no pictures.

[JB848]

OK if no pictures it didn't happen?

[ineedanap]

OK if no pictures it didn't happen?

Lots of pictures of a full rebuild...Nearly identical to a GS...seriously looks the same...  

http://gstwins.com/gsboard/index.php?topic=40821.0

Differences from photos.
1.  Use a 1/2 inch rachet instead of a wrench
2.  Pretend the damper adjusting rod isn't there.

Fork oil change is much much much simpler.  

[DoD#i]

2.  Find a 2x4 and cut it to the right length to jam between floor and engine mount to hold front up.  Alternatively, you can put a bunch of weight on the tail of the bike to lift the front end up as well.
3.  Loosen (only a turn or so) but don't remove fork cap.  It's a 1/2 inch rachet square under the rubber cap.  

Hmm. I can't do 3 with out doing

2.1 (remove handlebar clamp bolts)
2.2 frig about with the handlebar to keep it from dangling awkwardly by the control cables

To get enough space to pop the 1/2 inch ratchet in there.

[ineedanap]

Thanks, nice catch.  I was spoiled with 89 clipons and never had to worry about that.  I'll correct it.  

[JB848]

A GS rebuild not another bike come on?

[ineedanap]

A GS rebuild not another bike come on?

I realize I come off sounding like a jerk and that's not my intention.  What I'm trying to say is that if you're waiting for photos before you dive in, you're worrying too much.

On a fork oil change you can see every single part except for 3 just by standing next to your bike.  What could you possibly need a picture of?

Seriously, it's super easy.  I'm sure you can do it.  Try it and take the photos for us if you want.  You'll find there really is nothing to take a picture of.

Having said that, I'll drop it before I sound like more of a jerk.  Good luck.  

[FatBastard]

i had to do this a little while back, I lossened the bolts holding the forks in the triple tree and slid them out both together with the front fender and all(minus wheel of course), worked like a charm, took 15 mins and a mtn dew now the oil