This is one of the better modifications for the GS500. Same as with the progressive front fork spring modification, this one improves the handling of the GS drastically. Because the rear end of the GS is raised several centimeters (the GSXR shock is 3/4 inch longer than the OEM shock), the bike will follow your chosen line in corners much better. Also, when riding with a passenger the bike will handle much better and it won`t sag down to the bottom anymore, like the old shock does.

The rear shock mentioned here is a GSXR750 shock. But watch out, because not all GSXR750 rear shocks will fit. Only the shocks from the bikes made in the year 1989, 1990, 1991, 1992, 1993, 1994 or 1995 will fit the GS. Others are too long, or have the gas reservoir mounted on the shock itself which causes trouble mounting it under the seat. There is too little room for that reservoir. I got my shock from Ebay.com The price for a second hand gsxr750 rear shock differs from $10,- to $100,-. When you find one, beware of little leaks in the shock or the gas reservoir. Also pay close attention to the connections of the air hose to the shock and the reservoir. Make sure there are no leaks or cracks. Also make sure the upper ball bearing works. Mine didn`t. When there aren`t any leaks or cracks and the bearing works fine, make sure you don`t pay too much for it. $50,- for a secondhand shock is enough. Don`t go higher in price than $60,-.

The gsxr750 shock will fit the GS500 with only a minor modification. Put the bike on the centerstand, but put a board (at least 1/2 inch thick) under it first. You will need the extra clearance since the GSXR shock is longer. Remove the rear wheel for more space to work (it is not necessary, but it will give you some more clearance to work and will make the mounting easier). Now remove the old shock and the shock linkage. Take the GSXR shock and mount it to the shock linkage (it is no longer on the frame at this point) with the lower end of the shock (the lower end, where the air hose is not attached). Mount the GSXR shock to the point where the lower end of the old shock was mounted on the shock linkage. Now turn the shock linkage as far as it goes. The angle the GSXR shock makes with the shock linkage (angle alfa, see picture below) should be at most 30 degrees, the less the better.

See picture below:

This is not the case. Both sides of the bottom end of the shock will hit the edges of the shock linkage. This means the GSXR shock has to be grind a little bit, or the shock linkage. Now you have to choices: 1. Grind the shock linkage (grind the area which is red), 2. Grind the GSXR shock (grind the area which is blue). In the picture below, the red color refers to option 1 and the blue color refers to option 2.

In my case, I chose option 1, grind the shock linkage, because the lower button on the GSXR shock, to adjust the rebound damping (see picture below, in the red square, and the grinned area, with the red stripes) was also hitting the shock linkage when I turned it to measure the angle Alfa When you choose option 2, click the picture in the photo menu at the end of this page.

Make sure the GSXR shock and the shock linkage can make an angle (angle Alfa) of 30 degrees or less (the less, the better), or the shock won`t fit onto your GS. If you don`t grind enough, the shock won`t lean forward enough to get the top bolt in while mounting it on your GS. When you`re done grinding, make sure you paint the grinned places, otherwise they will rust very fast! After the grinding and painting, you`re ready to mount the shock. All the stock bolts work. First mount the shock linkage the same way is it was mounted before this mod. The bike is still on the centerstand with the (wooden) board under it. Raise the swingarm, so that the holes of the upper and lower end of the GSXR shock are in line with the holes of the linkage points (one linkage point on the frame, and the other one on the shock linkage). Now mount the GSXR shock the same way as the old OEM-shock was mounted.

Below are some useful pictures:

(click image to enlarge)

Next thing is to mount the gas reservoir. This is described on page 2: