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Fork air 1982GS1000G where to fill?

  • Thread starter Thread starter Bjornis
  • Start date Start date
B

Bjornis

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Hi all!
First of allI must say thank you to all posters on this forum. Bought a 1982 GS 1000 G whit Vetter fairing last year and went trough the bike last winter, took everything down except gear box (was working fine). Searching this forum I have found a lot of answers during the rebuilding process. So now I have a bike that runs much better then when I bought it :-D. Even used it last week to pass my drivers exam \\:D/

Well to the actual question, I was going to check air pressure in forks but cant find where to. I have the clymer manual and from the picture I can see that in top of fork there should be a "vent" there but I cant find it. On the top of fork I have a rubber thing that i can remove but there is only a big screw that goes down in to the fork.

When I boght it the seller said that he had rebuilt the forks previus year, could it be that he used progressive springs (never thought of asking cause i didnt know about them then)? Can I check if I have progressive?

Let all the visdom of you Gurus out there fall on me :-D.

Happy and safe riding to you!!!
 
Hi Mr. Bjornis,

Right at the top of each fork you should see a chrome cap with a 12mm nut on the top. The fork air valve stems are under these caps, one for each fork. In the crummy picture below you will see an air pump connected to the valve stem on the left fork.

forkair.jpg



If your progressive springs are stiff enough, you may not need air at all. You may want to try heaver fork oil. I hope this helps.

Thank you for your indulgence,

BassCliff
 
Got nothing like that in the top, all I have is a 22 mm (guess that is the top screw, take that one out and the springs will come out) whit a flat screw inside it.

Can i check if I have progressive?
 
Mr. Bjornis,

It sounds like the valve stems were replaced with caps after the new springs were installed. Perhaps you need not worry about air in your forks. That picture is from a GS850G but I can't see your bike being different there unless it's been modified from stock.

I have not installed a Progressive spring king in my front forks yet. Perhaps someone who has will let us know if that kit comes with new fork caps without air valves.

Sorry I can't be of more help. That's my story and I'm stickin' to it. :-D

Thank you for your indulgence,

BassCliff
 
Seems like it is replaced, clymer manual looks close to your picture.

Will see if anyone can confirm it.

Thanks for your help.
 
Bjornis said:
Hi all!
When I boght it the seller said that he had rebuilt the forks previus year, could it be that he used progressive springs (never thought of asking cause i didnt know about them then)? Can I check if I have progressive?
Click to expand...

If it dives like a half shot duck when you kit the front brake it wasn't rebuilt right. You will have to take it apart to see what you have otherwise. I would be calling the previous owner!!
 
I dont have any big problems with the front end, just would like it a little stiffer. If I do a hard stop it bottoms out but feels pretty normal otherwise. Previus owner was lighter than me so it might be setup right for him.

If it is progressive I should be able just to open them up and add/change preload on the springs or am I wrong on this?
 
fork air

fork air

I'd forget about adding air. Compressed air added to forks never seemed to work as well as they were thought to be able to. From all accounts, you are better off with the progressive-rate springs you have.

"Progressive Suspension" is a company name. Search for their web site, it's quite informative. They make springs that get progressively stiffer as they are compressed, while a straight-rate spring takes the same amount of force to compress the last inch as it does the first inch. Both have their adherents, but Progressives seem to work well for street use and don't cost much. In your case, cost=0 since they came with the bike.

I'm not sure you could tell by looking if they are stock or Progressive's. Unlike the evenly-spaced coils on a straight-rate spring, a progressive-rate spring usually has coils closer together on one end. But it could be the stock ones did too, I had one bike like that.

Generally add a little more preload to keep it from diving so much on hard stops. But not too much (i.e. maybe 10 mm max), else it gets real harsh.
 
Bjornis said:
I dont have any big problems with the front end, just would like it a little stiffer. If I do a hard stop it bottoms out but feels pretty normal otherwise. Previus owner was lighter than me so it might be setup right for him.

If it is progressive I should be able just to open them up and add/change preload on the springs or am I wrong on this?
Click to expand...

Normally one would change to heavier weight oil but you don't know what he put in there. Time for a phone call. Competition fork oil has a pretty crazy weight..you could by a bottle of that as it's 10x more than stock.
 
Bjornis said:
I dont have any big problems with the front end, just would like it a little stiffer. If I do a hard stop it bottoms out but feels pretty normal otherwise. Previus owner was lighter than me so it might be setup right for him.

If it is progressive I should be able just to open them up and add/change preload on the springs or am I wrong on this?
Click to expand...

IMO, you will be better off to just run with the progressive spring set up. The air gradually leaks from the shocks over time and you aren't always aware of the deteriation in handling until it's to late.
I would suspend the front end of your bike and carefully unscrew the top caps avoiding being hit in the eye by an unfriendly spacer and spring.
Check the length of the spacer above the spring and fabricate a longer replacement out of heavy walled PVC. Start out at 15mm longer than is presently fitted and road test with the new preload. If it's now too stiff, reduce the length by 5mm and try again.

I am currently fitting progressive springs to my '79 850. To my surprise,the previous setup had progresssive springs. They are wound differently to the new springs and are made of smaller diameter wire than the new ones.
The new springs are thicker and 40mm longer than the old ones.
I have added an extra 6 mm preload than recommeded as a trial. I'm also adding ATF instead of fork oil, as it will be more consistent as the fork temperature rises, with no foaming issues to contend with. I prefer my rebound to be a little softer.
If it doesn't work as expected, it's a simple job replacing the oil and the spacer length. I'm waiting on some seals, so I can't give you any guidelines for preload as yet.

Good luck with your trials.
 
Last edited:
49er said:
I'm also adding ATF instead of fork oil, as it will be more consistent as the fork temperature rises, with no foaming issues to contend with.
Click to expand...
Personally, I would stay away from ATF, unless it is specifically called for in a manual. I have heard that ATF has no consistent viscosity from one brand to another and may range from 2w or 3w to about 10w. I would rather stick with something that is designed for use in forks, like fork oil. Progressive Suspension recommends 15w fork oil when their springs are installed. I found that a bit harsh for my tastes and installed 10w instead. Much smoother ride without giving up control.

And..."foaming issues"? Are the roads down there that much rougher than they are here? And how can you tell if the oil is foaming? If the oil is foaming, chances are that the level is too low and the damping mechanism is riding above the oil level. As the suspension moves, it is plunged through the surface repeatedly, causing the foam. Raising the fluid level will keep the mechanism in the oil, intead of above it, with more consistent performance.


.
 
What do you weigh?

I have progressives in mine with about 45mm of spacer from memory & 15wt oil. Fine for me but I'm only 165lb. Someone with more weight might want to put a bigger spacer in.

Sounds to me like you could crank up your preload using those adjusters a notch & then try renewing the oil.

If you're heavier than me try 20wt.

Mine never seem to bottom out.

Dan :)
 
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