1982 GS550L front forks - Air Suspension?

[Guest]

Before I tear into these to replace what looks like a leaking seal, I need to know what I am getting into. These look exactly like regular oil-filled forks, but there is a caution sticker warning to only use nitrogen or air and giving a max pressure of 250kPa. What on earth? There is nowhere on these forks to add or adjust any air pressure. What are they talking about?

[Tom R]

Isn’t there a shrader valve under the caps on top of the fork tubes?

[Grimly]

There could well have been air-assisted forks on it when it left the factory, but some PO has replaced them with non-air ones. You're probably better off that way, as all you have to worry about is getting the springs / spacers right for your weight.

[alabamatom69]

well I am a big dummy. Yes there is. SO......

Rebuilding.....

The manual I have doesn't show air suspension, just standard oil-filled suspension. Is there a how-to anywhere for these?

[Big T]

The only difference is that air is added for additional spring rate
Most here just swap in a modern spring and don't use the air.

[Rich82GS750TZ]

https://drive.google.com/file/d/1UqX1j7ptsuV7rFEumeKuvzerU5MAKHNi/view?usp=drivesdk

you can download this supplement from my google drive. I'm not sure but your forks may be the same as the '82 750E or T. If not the same size, at least similar. At least it explains pretty well what's involved in disassembly and reassembly.

[Steve]

The manual I have doesn't show air suspension, just standard oil-filled suspension. Is there a how-to anywhere for these?

Well, just so you know, ... virtually ALL front suspensions "back in the day" contained metal springs and forced oil through specifically-sized holes to damp the motion. They ALL had air in them, and when the caps were sealed, it was trapped and became an auxillary spring. Some bikes went a step farther and added an air valve so you could add MORE air, for even more spring rate.

The rebuild procedure is identical. However, whether you have air-assisted forks or not, the springs are likely shot after 35+ years, so replacement is recommended. One of the forum favorites is Sonic Springs. Using their rate calculator, order the springs for your bike, riding style and gravitational attraction. Add the correct amount of 10w oil, it will feel like a new bike.

The bonus here is that with the proper springs, you will not need to add any air, so your ride will remain comfortable.

.

[alabamatom69]

Thanks for the help

[Rob S.]

My '82 also was built with air assist forks. Mine has the valve on the 'equalization' tube that runs between the forks. Broke it in last crash, but have the parts to restore it. Of course I installed new springs.

Just a note: if you ever wish to restore the air assist, remember you'll need a special, purpose built hand pump (gauge is usually part of it), as these are very small amounts of air we're talking about. If you try to use an air compressor for tires, you'll blow out your fork seals.