fork oil change

[stash]

Hi, i am from the airhead section but a friend has an F800GS and wants to change the weight of the fork oil. Any recommendations as to which heavier than standard oil he should try and also quantities for each leg. They seem like good machines, but there not airheads. Thanks for your time. Stash.

 

[stash]

Hi, i am from the airhead section but a friend has an F800GS and wants to change the weight of the fork oil. Any recommendations as to which heavier than standard oil he should try and also quantities for each leg. They seem like good machines, but there not airheads. Thanks for your time. Stash.

Well it seems that either no one has any ideas on changing fork oil(do you all run off to the dealers when things need doing) or strayed airhead visits are not wanted.

 

[v8legend]

There are a few threads on here re fork oil, so perhaps try the search.

You don't say why he wants to change the oil? There's not a whole lot wrong with the standard set up.

Remember, unlike your airhead, these bikes are relatively new, even the earliest ones are only just coming out of warranty. So not too many have been mucked about with.

 

[thomo57]

Well it seems that either no one has any ideas on changing fork oil(do you all run off to the dealers when things need doing) or strayed airhead visits are not wanted.

I recently fitted the Hyperpro spring lowering kit, which involves removing forks, draining & refillingthe forks.
The Hyperpro fork oil supplied is SAE10, heavier than standard, fill to 110mm, you need about 1.4 litres.

see below for tips & pics, thanks to Dave Ett from this parish...
http://www.ukgser.com/forums/showthread.php?t=229263&highlight=hyperpro

Hope this helps

 

[stash]

There are a few threads on here re fork oil, so perhaps try the search.

You don't say why he wants to change the oil? There's not a whole lot wrong with the standard set up.

Remember, unlike your airhead, these bikes are relatively new, even the earliest ones are only just coming out of warranty. So not too many have been mucked about with.

Thanks for your input gsers. His thinking is that the front end dives when braking, mind you he had a 1200gsa with telelever front end and that was the polar opposite. I suspect the transition from the two bikes has given the illusion of excessive front end dive. If we increased the weight of oil to 15sae this should firm things up, but what quantity do we need in each leg. We intend to keep standard springs and ride height. Cheers, Stash.

 

[thomo57]

stash

Not sure of the precise liquid quantity, but you will need to buy two litres.
With the fork well drained and spring, lower plastic spacer removed fill oil up to 110mm from top of fork tube, use a small tape measure and ensure the fork is vertical.
With two litres you will have about 0.5 litre left over.

 

[Sooty09]

The manual says 765ml 0f SAE7.5 hydraulic fluid for the initial fill. Then with the spring removed and the spacer installed (with all air bubbles removed) the level from fork leg top to fluid with forks fully compressed is 60mm.

 

[stash]

The manual says 765ml 0f SAE7.5 hydraulic fluid for the initial fill. Then with the spring removed and the spacer installed (with all air bubbles removed) the level from fork leg top to fluid with forks fully compressed is 60mm.

Hi there fellow gsers,
Thank you for your input, on my 100gs the forks have 430ml in one leg and 410ml in the other, this is because compression and damping are catered for individually by each fork leg. Question, when you say 765ml is that for each leg.What are the thoughts on increasing fork weight to 15sae, most of his riding is on tarmac. Regards, Stash.

 

[Sooty09]

I had to look at the work shop disk again to make sure, it says per leg. Seems like a lot of oil, my older Triumphs had 120cc per leg,

 

[Dave Ett]

Your older triumphs aren't a new 800GS are they? What a dumb comment. The 800S doesn't have points and right hand gear change either!

Despite being pointed to the thread about the hyperpro kit - which (if stash had bothered to read) has several people saying how much better their bike was with 10wt oil you insist on adding 15 wt.

Let us know how solid it feels - I do hope you're not planning on taking it off road!

 

[Dave Ett]

or strayed airhead visits are not wanted.

When your first post has the subtle insult "They seem like good bikes but they're not airheads" what did you expect?

 

[stash]

When your first post has the subtle insult "They seem like good bikes but they're not airheads" what did you expect?

Hi Dave, good to see that fellow gsers are passionate about their rides , i personally prefer the agricultural nature of the airhead, but then neither spelling nor sophistication are my forte. Your post,though delayed, was greatly appreciated.
I did read the link to your article on the hyperpro kit and though informative to those requiring a less elavated position it seemed an expensive and convoluted remedy for my friends delema of fork dive, imagined, or not. It seems that your ignorance of fork oil viscosity as used by BMW,excuse my paraphrasing your quote, does leave a certain amount of experimentation for those willing to venture into the unknown. And that was always BMW's intention when developing the GS range.
By the way, I found Sooty09's response to my question helpful and civil, your impression of his comments being "dumb"may be an opinion born from you"elavated position", on second thoughts,with the hyperpro kit that will no longer be the case. Should i venture into this arena at a future date i will look carefully for any potential dumb comments that should slip from your lips. To all you GSers, thank you. Stash.

 

[Dave Ett]

Nothing to do with an elevated position, very much to do with the facts at hand.

An old triumph does not have 53mm long travel forks, so why on earth would it have a similar amount of oil in it?

 

[stash]

Nothing to do with an elevated position, very much to do with the facts at hand.

An old triumph does not have 53mm long travel forks, so why on earth would it have a similar amount of oil in it?

Hi Dave, interesting to read your comments on "fact". Can you inform me on which machine you refer to when mentioning "53mm long travel forks". I can appreciate progress in technology but even my airhead 100gs has somewhat better performance. Still i thought there must be a reason for my ludite nature. Take care, Stash.

 

[Sooty09]

Wow Dave Ett, you must be a Yorkshire lad, Sat what you like and bloody well like what you say.
Yes my old bike took 120cc thats why I had to check 765cc was per leg not total. It still seems a lot of oil when so many efforts are made to reduce the unsprung weight. Is all this oil considered unsprung or not, please explain as you seem to know everything, no dumb answers please.
By the way my F800GS has 230mm of front fork travel, twice my T120Triumph (2 x 120cc = well work it out yourself). If your bike only has 53mm of travel as you quote I suggest you return it to your dealer. If you meant 53mm diameter forks again take it back, they are 45mm diameter.

Also a bit of education for you, my last T120 Bonneville had Lucas electronic ignition, a left hand gear change and a working electric start.

Have you no accurate facts to offer?

 

[Dave Ett]

Wow Dave Ett, you must be a Yorkshire lad, Sat what you like and bloody well like what you say.
Yes my old bike took 120cc thats why I had to check 765cc was per leg not total. It still seems a lot of oil when so many efforts are been made to reduce the unsprung weight. Is all this oil considered unsprung or not, please explain as you seem to know everything, no dumb answers please.
By the way my F800GS has 230mm of front fork travel, twice my T120Triumph (2 x 120cc = well work it out yourself). If your bike only has 53mm of travel as you quote I suggest you return it to your dealer. If you meant 53mm diameter forks again take it back, they are 45mm diameter.

I did mean the diameter, and yes it seems they are 45mm not 53 - either way that's a damn sight wider than an old triumph!

I would argue the fork oil is unsprung, since it is not affixed to the upper part of the forks, but I'm happy to have it explained otherwise.

And I was born in Lancashire!

Oh, and you didn't state which old triumph, so I picked a very old one to highlight how different it was.

 

[stash]

I did mean the diameter, and yes it seems they are 45mm not 53 - either way that's a damn sight wider than an old triumph!

I would argue the fork oil is unsprung, since it is not affixed to the upper part of the forks, but I'm happy to have it explained otherwise.

And I was born in Lancashire!

Oh, and you didn't state which old triumph, so I picked a very old one to highlight how different it was.

So Dave,while we are on a roll could i please tap into the mine of information that this site offers, with some obvious exceptions, and ask what effect the 15W SAE fork oil would have on road/off road characteristics. Stash.

 

[Dave Ett]

I think you'd find it seriously hard, overdamped and would jar the forks at every bump.

I did a bunch of gravel tracks and the like in Morocco on standard BMW suspension, and it was really good off road, just a little too soft on it. Having now got 10wt oil in I find it's a perfect mix for both types of riding.

I ran 15 wt oil in my FJ1100 for a while, and found that too hard. It came from the factory with 5wt, so that was a little more extreme than the GS, but it was a pure road bike.

Changing fork oil isn't the hardest job to do, but I would recommend trying 10wt before going to 15 personally.