1981 GS1100EX Front Forks Air Joint O-Ring Part Numbers

[ColdStart]

Hello, Fellow Riders,

I will be overhauling my front forks and actually installing RaceTech Gold Valve Emulators on my 1981 Suzuki GS1100E. I have installed these on my 1981 Suzuki GS750E and it has completed the bike into being a complete fun machine.

However, as I am putting together a parts list, it looks like the online parts retailers do not have the complete parts diagram that includes the air joint assemblies. Therefore, I do not have the parts numbers for the o-rings used in the air joint assemblies that I will be replacing.

I found a complete diagram in the Clymer Manual for my model year. It clearly shows the parts in the diagram and names them in the description. However, it does not list the part numbers. I have attached an image of the Clymer manual page below.

I am also having difficulty finding an online retailer who has the other o-rings used in the forks, although I have the parts numbers for those (see below).

So, I am looking for the following help:

1. What are the part numbers for the air joint o-rings used in the air joint assemblies?

2. Who may have these air joint o-rings available?

3. If Suzuki parts dealers do not have these air joint o-rings, what size are they and what material are they made of? I will be removing the old ones during the overhaul, but I am not sure that I am skilled enough to figure out the exact, new o-ring measurments from the used samples.

4. Which online retailer may have the following 0-rings (not part of the air joint):

51435-49200 (o-ring above the oil lock piece)

51148-49200 (o-ring below the oil lock piece)

5. Any other recommendations regarding procuring these parts?


Thank you very much.


Clymer Manual forks diagram with air joint assembly shown

Front Fork Assembly with Air Joint.png


Online Retailer Diagram 1981 Suzuki GS1100EX: Does not show the air joint assembly

Could not be displayed here, due to attachment number restriction.

[ColdStart]

Here is a better image of the Clymer Manual Diagram


Front Fork Assembly with Air Joint copy.jpg

[ColdStart]

And this is the online retailer diagram of the 1981 Suzuki GS1100EX that does not show the air joint that this motorcyce has. It does show the two other o-rings that are not available:

Online Retailer Diagram copy.jpg

[wilsonsandy07]

i just replaced mine with some generic nitrile o rings i had in the shop, i can send you the size when i get home i forget off the top of my head but my air system was leaking and after replacing its all good to go

[ColdStart]

Hi,

Well thank you for the offer. I have now taken the forks apart and will be measuring the o-rings, but as I said, I am not sure how accurate my measurements may be, based on the rings possibly being deformed, my lack of experience, poor vision, etc.

I did find out from the RaceTech website that the o-ring under the oil lock piece is 14mm OD x 2mm thick. I then noticed that I had one of these in a Harbor Freight assortment in my toolbox. So that's good.

Another thing I learned is that the air-joint parts are depicted in the Steering Stem diagram on the online parts stores.

So, if you do not mind quoting the 0-ring sizes here, I would appreciate that. Cheers!

Steering Stem Diagram 1981 Suzuki GS1100E .jpg

[bwringer]

The '83 GS850G had a very similar crossover tube setup, and the o-rings are depicted there. 09280-06005 -- the 90280 indicates an o-ring, and the 06 indicated a 6mm ID. No indication of the thickness.

I'd strongly suspect this is the right part number. Suzuki didn't like to design new parts.

https://www.onlinecycleparts.com/oemparts/a/suz/50d401e7f8700230d8b4e5ea/steering-stem-model-d

This is the same as one of the 0-rings needed for the cam chain tensioner rebuild, the one used for the lock screw:

https://www.bwringer.com/gs/camchaintens.html

Way back when I made this tutorial, I measured this o-ring at about 1.8mm thick.

[salty_monk]

I would just get a kit of multi around the right size & do it as I went... Usually a bit of forgiveness in O ring sizing.

[Rob S.]

Isn't the accepted procedure just to install new (straight rate) springs and block off the air feature?

(I did that, even though I have the parts and special air pump should I ever wish to return her to stock. Which I won't.)

[Nessism]

Isn't the accepted procedure just to install new (straight rate) springs and block off the air feature?

Yes! This is more important than the emulators. Straight rate springs from Sonic! The former owner is a member here.

[Rob S.]

Yes! This is more important than the emulators. Straight rate springs from Sonic!

I put .90 springs in (Race Tech) about a decade ago. Didn't plan on late fifties/early sixties weight gain, though.

[ColdStart]

The emulators work well: they allow for proper slow compression damping and add fast compression damping. The proper linear spring rate, chosen by rider weight and sag goal, just requires one spring rate. This allows for riding well on the street, over slower, gradual, regularly encountered unevenness in the road.

The fast compression - think riding over a two-by- four - works by opening up additional flow channels for such impact. I love how this has improved my riding experience during very spirited riding on New England backroads on the bikes I have installed these on. On one of my bikes a few years back , a BMW F700GS, I installed progressive fork springs first. That gave me some improvement, especially with heavier loads but going over harsh , fast bumps, still unsettled the front. There was some off-roading involved there, too, so I was pushing the limits of that bike a bit. . I installed the gold valve emulators and the riding experience in all sorts of terrain improved. I can highly recommend their installation.

Anyway, I was able to measure and procure all o-rings required: The JIS P5 are required inside the air lock around the valves and around the rebound damper assembly in the damper rods. 4 JIS P36 O- rings are required for the seal of the air locks around the forks. A total of two 14 ID X 2 CS are required to create a seal at the bottom end of the damper rods.

I will be setting the airlocks to atmosphere. The air pressure adjustment can still be used, but I will likely not need to do that. On my 1981 GS750E, armed with gold valve emulators, I set the air pressure to atmosphere which means that I did not add any air-pressure. Things are good.

Thanks, folks for chiming in.

PS: Nessism, the engine runs like a dream: Thanks for sending me the carburetor o-rings.