Suzuki GS500 Fork Upgrade

Back in 2003 I documented the build of my 1993 Suzuki GS500 project bike. The goal was to build a modest GS500 into a cheap, street legal, but capable track bike using inexpensive and readily available performance parts from Suzuki’s GSX-R parts bin.

After previously upgrading this GS500’s rear shock I set out to improve the front suspension as well. I picked up a nice pair of forks, triple clamps, clip-on bars, and a fender from a 2002 Suzuki GSX-R 600. Though dimensionally larger than the GS500, due to the GSX-R’s lighter aluminum frame the bikes weigh in about the same, so the GSX-R forks didn’t need to be re-valved for the GS500.

The first challenge in this project was making the new triple clamps work in the GS500 frame due to the GSX-R’s longer and thicker steering stem. The GSX-R’s aluminum steering stem is hollow, so machining it down to fit the GS500 frame neck was not an option. I took both stems to a machine shop and had them make a new stem combining the lower press fit dimensions of the GSX-R stem with the correct upper width and length to accommodate the GS500 frame. I also needed a bushing to fill the space in the upper triple clamp left by the narrower stem. Once the new steering stem was press fit into the GSX-R lower triple, I began assembly.

 

It should be noted here that Suzuki used the same steering stem widths and steering assembly bearings in all of their sport series motorcycles in 1993. Hindsight being 20/20 it would have made more sense to use a 1993 (or similar year) GSX-R front end which, assuming the lower triple clamp isn’t significantly thicker than the GS500, would likely have allowed me to simply press the stock GS500 steering stem into the GSX-R triple clamps.

Reassembly begins at the triple clamps using fresh bearings, grease, and dust seals. Then tighten the upper retaining bolt to spec and check everything for free range of motion. In my case the steering stops on the lower triple clamp interfered with the bike’s frame so I ground them down to allow for a better turning radius. Next I slid the fork tubes into the clamps, making sure they were equally spaced, tightened the pinch bolts, and installed the clip-ons. Now attach the wheel, making sure the direction of the tire rotation is correct and bolt up the brakes and fender.

At this point I ran into some more challenges. The later model front axle is significantly thicker than the stock GS500 piece, so the mechanical speedometer drive is not compatible. There are reasonably priced aftermarket solutions, or with more modern technology you could mount an iPod or smartphone with a GPS speedometer app. Again, in hindsight it would have been simple to adapt if I’d used an older GSX-R front end.

After the suspension mods we took the GS500 to Virginia International Raceway for a track day.

 

Before you tackle a project on this level, understand that retrofits like this often come with unplanned impacts. In the case of this project the steering lock no longer worked in the absence of steering stops, and the speedometer situation could be cumbersome at times. All of that said, although I ran into some unexpected cost and complication I was thrilled with the results. This upgrade drastically improved the handling and feedback from the bike, and finding replacement parts is still as easy as locating the nearest Suzuki dealer. It also looked great and was a great conversation starter in the pits and at meets.

 

Check out the rest of our Suzuki GS500 posts!

By | 2017-09-12T19:52:16+00:00 January 10th, 2015|Motorcycle Projects|0 Comments

About the Author:

I’m a lifetime car guy with a broad interest in just about any type of self-propelled machinery, and racing. I have a soft spot for under-appreciated marques, which often gets me in trouble with oddball projects.

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