Hi all.

Just had to post a word or ten about changing my GS fork oil.  My GS is nearly 9 years old now.  I reckon the fork oil has never been changed before (my bike's done 15K - 10K of that is what I have done in the last 18 months).

You may have read my posts about Modding and Insurance and know that I changed out my progressive springs for the stock springs because my insurance didn't cover non-stock forks (only my stupid underwriter - no other insurer here in the UK are so strict!).  Anyway, the stock springs suck, right...or do they?.

Well I pulled the forks off the bike yesterday (Saturday) and was pleasantly surprised at how easy a job that was (it was,however, a very long job because we kept having rain showers and I'm working in the yard - no garage ).  I jacked the bike up first with a scissor jack and then put car axle stands under the frame members just below the engine mounts.  Pretty stable but I had to be careful because the bike was not strapped down, so it could be wrestled off the stands if one used to much 'muscle'.

Anyway, pulled the fork tubes having first loosened the fork tube caps, then carefully removed the caps and springs/spacers & washers and drained the oil with a gentle 'pumping motion' (or 'stroke' as the Haines Manual puts it).  I'll tell yer...the crap that came out of those tubes!!  It was an unhealthy looking dark grey oilly/watery mess, like oily puddle water!  There was also some fresh metal particles which were as a result of the removing/replacing of the fork caps (you know, those abortive attempts when you begin to realise you are begining to cross-thread the cap/fork tube threads and back-off).  I really worked at pumping all that old oil out of the tubes.

Then, when I was ready to put the new oil in (15W), I made up some 'dipsticks' out of paper card with the relevant air gap spaces marked (105mm in my case).  This worked very well and I am pretty confident I got as near as dammit to 105mm air gap in each tube!  Re-assembly was a breeze - I put the springs and washer in each tube then lightly screwed the cap back on then fixed the tubes back in the triple trees.  Once installed back in the triple trees I then put the spavcers back in and secured the caps (much easier to do on the bike because I don't have a workshop and therefore no acces to a vice).

Anyway, it is now Sunday (I was too knackered to test ride the bike Saturday) and rode a good 60 miles round trip today (the M1 and A6006) and was absolutely stunned by (and absolutely estatic with) the handling improvement!   It was better than when I had dropped the proggressives in!!!

I won't prattle on any further other than just to say that if your front end performance is a bit lacking and, well, a bit too soft, then change yer fork oil for some fresh 15W - you may very well be surprised at the transformation in your front-end performance (ooh er, missus!)...

bassman

Yeah I did the same before switching springs. I'm ahhhmmmmm (WAS) 270lbs so I went with the 30w the thickest I could find around here and was stunned by the difference. I didnt have to remove my forks though....

http://gstwins.com/gsboard/index.php?topic=43294.0

this is one of my top priorities, when i bought my bike the front forks were horribly bent so i bought some cheap used forks out of a 91 gs with 20k miles on em and they're great, don't leak and are straight, but they bottom out so easily, even on braking, and i'm only 150lbs!

I'm about 220lbs so I'm very surprised that your forks bottom out when you weigh 150lbs!  Sounds like they could definitely benefit from an oil change. 

Before changing the oil, I took the precaution of buying new oil seals and dust covers.  I didn't need to change the seals but I did change the dust covers.  The right fork's (right from the riders viewpoint) dust cover had begun to deteriorate and had let moisture into the space above the oil seal.  This in turn had lead to the spring that holds the oil seal to begin to corrode.  All I did was spray some WD40 onto the spring and wipe it all clean (I'll change the oil seal spring for a new one eventually).  This revealed no deterioration of the seal itself, or any signs of leakage, so the loss of performance in my forks must simply have come down to the age of the fork oil.  Maybe moisture/dirt had penetrated the the seals over time and had contaminated thre oil.  After 9 years it's not beyond the realms of possibility.

I note somebody had posted a question about whether they should change their fork oil as part of routine maintence and got some bemused replies.  Well, I guess you wouldn't be wanting to changeout the fork oil every six months like you might with the engine oil.  But every 2 to 3 years if you ride all 4 seasons nearly everyday like I do may be beneficial to the internal parts of the fork.  A regular fork oil change is preferable to the hassle (and expense) of rebuilding the fork internals!

bassman

Quote from: bassman on April 12, 2009, 02:06:50 PM


You may have read my posts about Modding and Insurance and know that I changed out my progressive springs for the stock springs because my insurance didn't cover non-stock forks (only my stupid underwriter - no other insurer here in the UK are so strict!).  Anyway, the stock springs suck, right...or do they?.

That's wild. Technically, your forks ARE stock, it is your fork springs are not. So you can argue there.. Why the h3ll did you tell them anyway? They don't know any difference neither will open the forks investigating the claim. Utter BS (IMHO).

I have progressive springs and will never go back to stock. I also used 15W last time but now think about switching back to 10W. The ride is a bit firm to my taste. I am not a heavy guy at 180 lbs (~80kg).

Are you suggesting he should knowingly lie to his insurance company, which technically is fraud and very much illegal and also run the risk of having insurance cover withdrawn in the event of an inspection following an accident?

Dont make the mistake of thinking the insurance companies are daft, they are not, they know what goes on, they know people tell lies, they know what to look for when they make their post-accident inspections and they know how to avoid having to pay out large amounts of their money.

Beep beep beep...Groundhog Day!...

bassman

Quote from: sledge on April 14, 2009, 12:24:45 PM
Are you suggesting he should knowingly lie to his insurance company, which technically is fraud ...

It's BS. As I said the forks are still technically stock. He did not change forks (i.e. weld on a Katana fork or something, as some on this forum do) which affects the steering geometry and could be dangerous if done incorrectly.

People alter suspension in their cars, for example lower the car and they do not get BS exuses from insurers to cancel their coverage. If I follow your logic changing my car rims to be an inch taller should affect my insurance because I altered the way the car is designed to operate. Again, total BS.

I sense it's his insurance just does not want to give him coverage (for whatever reason). Just go find another insurance company.

Reminor, I did change my insurance!

My insurance came up for renewal from today and I re-arranged it some weeks ago with the same agent (a big UK company) but with a different underwriter.  Honestly, it's no big deal.  I was surprised (pleasantly, and somewhat amused by) the passion of some of the responses!  Of course its BS that fitting better springs that improve the handling should not be covered by a particular insurance underwriter.  But, it is what it is.  If I accept a quote from that company but did not specifiy that I might want to modify the bike at some time in the futre then that is entirely my problem.

Anyway, fess-up time (drum roll) I re-fitted the progressives months ago (someone help that lady who just fainted in the second row please).

Yeah, I'm bad (step aside John Goodman).

Bassman

Bassman, thanks for your fork oil change write-up.  You made it sound so much more straightforward than the instructions in the Haynes manual.  One of my forks has begun to weep so I'll be doing it soon.  I will print your post and refer to it as I go along.  I don't have a vice either, (other than wine, women and song!) or a bench for that matter, so I appreciate your write-up very much indeed! 

FWIW, the local racing suspension expert suggests 30W oil. Or brazing up and drilling out smaller holes for the rebound damping.

I haven't tried it, but 20W is on my list. As are .95kg/mm springs.

Quote from: bassman on April 12, 2009, 02:06:50 PM
Hi all.

Just had to post a word or ten about changing my GS fork oil.  My GS is nearly 9 years old now.  I reckon the fork oil has never been changed before (my bike's done 15K - 10K of that is what I have done in the last 18 months).

You may have read my posts about Modding and Insurance and know that I changed out my progressive springs for the stock springs because my insurance didn't cover non-stock forks (only my stupid underwriter - no other insurer here in the UK are so strict!).  Anyway, the stock springs suck, right...or do they?.

Well I pulled the forks off the bike yesterday (Saturday) and was pleasantly surprised at how easy a job that was (it was,however, a very long job because we kept having rain showers and I'm working in the yard - no garage ).  I jacked the bike up first with a scissor jack and then put car axle stands under the frame members just below the engine mounts.  Pretty stable but I had to be careful because the bike was not strapped down, so it could be wrestled off the stands if one used to much 'muscle'.

Anyway, pulled the fork tubes having first loosened the fork tube caps, then carefully removed the caps and springs/spacers & washers and drained the oil with a gentle 'pumping motion' (or 'stroke' as the Haines Manual puts it).  I'll tell yer...the crap that came out of those tubes!!  It was an unhealthy looking dark grey oilly/watery mess, like oily puddle water!  There was also some fresh metal particles which were as a result of the removing/replacing of the fork caps (you know, those abortive attempts when you begin to realise you are begining to cross-thread the cap/fork tube threads and back-off).  I really worked at pumping all that old oil out of the tubes.

Then, when I was ready to put the new oil in (15W), I made up some 'dipsticks' out of paper card with the relevant air gap spaces marked (105mm in my case).  This worked very well and I am pretty confident I got as near as dammit to 105mm air gap in each tube!  Re-assembly was a breeze - I put the springs and washer in each tube then lightly screwed the cap back on then fixed the tubes back in the triple trees.  Once installed back in the triple trees I then put the spavcers back in and secured the caps (much easier to do on the bike because I don't have a workshop and therefore no acces to a vice).

Anyway, it is now Sunday (I was too knackered to test ride the bike Saturday) and rode a good 60 miles round trip today (the M1 and A6006) and was absolutely stunned by (and absolutely estatic with) the handling improvement!   It was better than when I had dropped the proggressives in!!!

I won't prattle on any further other than just to say that if your front end performance is a bit lacking and, well, a bit too soft, then change yer fork oil for some fresh 15W - you may very well be surprised at the transformation in your front-end performance (ooh er, missus!)...

bassman

Thanks bill14224   I also gave the fork tubes a really good clean when they were off, and the triple trees a wipe inside where they grip the tubes.  A little WD40 or similar helps to ease the tubes back into the triple trees as well.  Remember not to tighten the triple tree pinch bolts up to the spec torque until you've got the spacers in and the caps tightened down.

As you know, I didn't replace the fork seals.  I think you need to be really careful when replacing them that you don't nick them.  I say that because on one of my fork tubes, the chrome had some corrosion spots.  i reckon that you could nick the seal with the corrosion if you were unlucky.  When I eventually do have to change the seals (probably the next time I change the fork oil) I was thinking that maybe smearing some light grease (like Vaseline) over the corrosion might help to ease the seal on without damaging the seal.  I've never done a re-seal so somebody on the site will probably have a view on it!

Good luck with the fork oil change and let us all know how you get on!

P.S.  I'm thinking of synchronising my carbs this weekend (gulp!).  I've got a Carbtune manometer and an auxillary fuel supply so I ain't got no excuses! (will have to make sure I've got the beer in the fridge for later after that - i'm such a wimp!!)

Bassman

I haven't synced carbs, but there is a quick and dirty way that some members use here that involves clear tubing and water.

We picked up the fiance's '99 with rebuilt forks and 15W oil.   It is REALLY NICE.  Nice and firm.

Quote from: bassman on June 17, 2009, 12:58:23 PM
Thanks bill14224   I also gave the fork tubes a really good clean when they were off, and the triple trees a wipe inside where they grip the tubes.  A little WD40 or similar helps to ease the tubes back into the triple trees as well.  Remember not to tighten the triple tree pinch bolts up to the spec torque until you've got the spacers in and the caps tightened down.

As you know, I didn't replace the fork seals.  I think you need to be really careful when replacing them that you don't nick them.  I say that because on one of my fork tubes, the chrome had some corrosion spots.  i reckon that you could nick the seal with the corrosion if you were unlucky.  When I eventually do have to change the seals (probably the next time I change the fork oil) I was thinking that maybe smearing some light grease (like Vaseline) over the corrosion might help to ease the seal on without damaging the seal.  I've never done a re-seal so somebody on the site will probably have a view on it!

Good luck with the fork oil change and let us all know how you get on!

P.S.  I'm thinking of synchronising my carbs this weekend (gulp!).  I've got a Carbtune manometer and an auxillary fuel supply so I ain't got no excuses! (will have to make sure I've got the beer in the fridge for later after that - i'm such a wimp!!)

Bassman

As I'm doing an average 5000 miles a year I invested in a Carbtune vacuum gauge and an auxillary fuel tank.  i've read the posts about the homemade varieties, but I thought that by the time I've faffed around buying the tubing,etc,etc I might as well buy a 'professional' job!

Bassman

Do you/anyone by chance have a link to a how to on this topic, that shows pictures, parts, etc?  I don't have a manual yet........ 

Do you happen to have a link to an article or diagram that shows how the fork oil can be changed, a step by step if you will?  I don't have a manual yet.   

There's lots of info on the board. For example, here's a post in the FAQ section:
http://gstwins.com/gsboard/index.php?topic=25706.0