I will soon be selling my upgraded suspension system (within the next month) from my R80gs 1991 model. (as I am completing a different bike project) If your interested in upgrading your gs then Pm me with your noted interest as I have not worked out a selling price yet. (so start saving yer pennies)
It comprises of a 3 year old Wilbers 641 rear shock absorber with remote high and low speed damping adjuster, rebound adjustment plus the additional 625 remote spring adjuster. The shock absorber is very adjustable to meet every demand your GS will ever need. It was originally built to spec for me to cope with Solo rider 80kgs (with bike gear on) solo rider plus upto 45kgs luggage and adjustable to carry a pillion also over and above the luggage upto 65 kgs. The shock was stipulated suitable for Dirt, Gravel, and Tarmac roads.
The Front suspension Upgrades consist of No longer available HPN Marzocchi fork cartridge inserts (not just springs) giving Marzocchi Magnum quality to the gs fork with 225mm travel. Fully adjustable compression and rebound damping. also if your really loaded up with 43 litre tank additional spacers to pre compress the springs in the inserts to allow for the extra weight.
The fork inserts improve the front end beyond belief over the standard fork set up and combined with the Wilbers rear transform the bm into a modern handling package. Regards Jake.

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If it is good to have one foot in England, it is still better or at least as good, to have the other out of it. jake

PM'd you a few days ago. let me know if didn't get through.