GS1100g forks

[Sidman]

Hi guys , thanks for the replies to my earlier post , I have looked at the workshop manuals and cannot find an air valve on my forks . My 1985 gs1100 has a rubber cap on top of the fork nut with a flat head screw underneath. Anyone know what the deal is . It is an Australian delivered bike if that makes a difference

 

[Steve]

I'm not sure that the Aussie bikes had air caps. :-k

You were instead blessed with adjustable pre-load.

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[Sidman]

I'm not sure that the Aussie bikes had air caps. :-k

You were instead blessed with adjustable pre-load.

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Is the adjustable preload a better system

 

[Steve]

For consistency, yes. Pressurized air has a tendency to escape, leaving you with just ambient air trapped inside the fork tubes. Having springs of the proper rate will eliminate the need for additional air. Many of us have replaced our stock springs and upgraded them with Progressive (brand) springs, Sonic springs or Racetech. Sonic and Racetech are straight-rate springs, which tend to work a bit better. Fresh springs, along with fresh 10w oil will do wonders for improving your ride.

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[GregT]

Is the adjustable preload a better system

For Australia, yes. Blow a fork seal in WA with air assist and one fork leg isn't carrying the load. Limp home - perhaps a very long way....
With what you have, a blown fork seal will simply make the bike very dirty, but it'll stay up. Much better.

 

[Steve]

Blow a fork seal in WA with air assist and one fork leg isn't carrying the load.

That depends on the bike. :-k

At least some​ of the early 4-valvers had equalizing tubes between the fork legs. I noticed it on an '81 1100E, I don't know if it was also on the 750 for '80/'81, or if it continued into the re-styled '82/'83 bikes. They only had one fill valve, and the forks were ALWAYS at equal pressure. :encouragement:

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[Guest]

you may have air collars right under the top triple.
there would be a short hose between fork legs with a single fill point (schraeder valve under a fancy cap) on the left hand collar.
BTW, air pressure and preload don't do the same things

 

[Sidman]

Thanks for the replies , definitely no air tubes anywhere , simple is probably better , thanks again

 

[Panozzi]

Hi Guys
Sorry for stealing the topic but I own a GS1000G -83 (GX) (European model, Sweden) without any air cap and it also has a rubber cap on top of the fork nut with a flat head screw underneath that you can adjust. The question isn't if its good or bad with or without air/or not air cap. The really hard part is to find out what amount of fork oil I should pour when a fork seal is done. That's where I am stuck........ The GS1000G FRM says 251ml per fork when its with air cap but is it the same with the adjustable cap??

 

[2BRacing]

Hi Guys
Sorry for stealing the topic but I own a GS1000G -83 (GX) (European model, Sweden) without any air cap and it also has a rubber cap on top of the fork nut with a flat head screw underneath that you can adjust. The question isn't if its good or bad with or without air/or not air cap. The really hard part is to find out what amount of fork oil I should pour when a fork seal is done. That's where I am stuck........ The GS1000G FRM says 251ml per fork when its with air cap but is it the same with the adjustable cap??

The specifications for the spring pre-load adjustable forks are as follows:

Oil volume: 213 ml
Oil level: 203 mm
Spring free length: 459 mm

The specifications for the air forks are as follows:

Oil volume: 251 ml
Oil level: 140 mm
Spring free length: 416 mm

The oil level is measured with the spring removed, and the inner tube pushed all the way down, and measured from the top of the inner tube.

These specifications are from the OEM Suzuki Supplementary Service Manual for GS1000G​

 

[bwringer]

I see questions over and over and over again about the quantity of fork oil required.

The QUANTITY of fork oil is entirely irrelevant, other than it may be a helpful approximation to make sure you have enough on hand.

The only spec that matters is the fork oil LEVEL. What matters most is that the fork oil levels are IDENTICAL.

Some folks adjust the fork oil levels a bit from factory spec to fine-tune; for example, it's common to go with a level 10mm higher (smaller number) in order to reduce the amount of "air spring" inside the fork. And if your oil level spec is 203mm, it's not going to matter much whether it ends up as 198mm or 205mm as long as both are exactly the same

To achieve this repeatability easily, overfill each fork leg a little, pump to remove the air, then slurp out the excess oil with a large syringe and a measured length of tubing.


Also, the fork oil quantities given in the manuals are dry, starting with completely empty and cleaned forks. If you're just changing/flushing the fork oil but haven't completely disassembled the forks, there's a significant but unknown amount of oil left in there. Don't just eyeball the amount in a baby bottle, dump it in there, and button it up. Overfill a little, operate the forks by hand to mix and remove air, then set the levels precisely by slurping out the excess.

 

[salty_monk]

A good way of "slurping out the excess" is to get the top off a spray bottle (simple green or similar). Hold it on the top of the fork. Cut the straw to the level you need below the bottle cap and then use the trigger to pump out the oil into a shop rag...
I have a few different ones on my shelf set for different forks these days.