Fork options

[Guest]

Looking to upgrade my 81 gs650ex. Need some opinions on forks maybe gsxr, I dont know much on how to do it.

[Rich82GS750TZ]

Welcome to the GSR
no info for you but here's a tip on using this site's search function in the upper right corner.
click on Advanced Search
In the Keyword(s) box, type fork upgrade
Change box to the right of that to Search Titles Only (this is the key to getting any worthwhile results on this site using the search function)
Click Search Now.
You may find a few things there worth reading.

[mmattockx]

Do your looking in the suspension & brakes forum, most of the info is in there. Here's a thread to get you started:

https://www.thegsresources.com/_forum/showthread.php?237305-More-modern-cartridge-fork-options-retaining-GS-wheels-amp-proper-revised-geometry

Mark

[Steve]

Biggest upgrade you can get, and very little money spent in the process:

Replace the springs with straight-rate springs. Sonic Springs are highly recommended.
Replace the fork seals.
Install 10w fork oil.
RaceTech emulators from MikesXS are also recommended.

.

[Chuck78]

Biggest upgrade you can get, and very little money spent in the process:

Replace the springs with straight-rate springs. Sonic Springs are highly recommended.
Replace the fork seals.
Install 10w fork oil.
RaceTech emulators from MikesXS are also recommended.

.

∆∆∆ what he said! Unless your fork tubes are in bad shape with any rust pitting or gouges or damage in the seal travel area between the dust boots and the triple clamps...

going with any other major fork upgrades like a cartridge fork will require some custom machining to fit your 15mm GS axle size into a much more modern and advanced cartridge fork designed for a 20 mm axle and wider spacing.

Of course you would also be upgrading to a much stiffer fork with larger-diameter tubes if you abandon the GS forks, but you can also look for a set of GS850, 1000, 1100 forks to get 37mm tubes. Yours are 35mm currently. Those will all bolt on with only minor modifications to the steering stops generally. You will need the matching axle and spacers most likely, they are probably 10 mm wider overall. Speedometer drive is also a spacer on these bikes.
As far as the modern forks also, you need to select the proper triple clamp geometry, just using the triple clamp that came with the forks that you are using is not appropriate as they are specific to the frame geometry they were intended for, as well as the front wheel size they were intended for. Without both of those being identical to the donor bikes original specs, i.e
swapping wheels and cutting & re welding the frame to change the rake to sportbike territory, you are going to end up with a slower steering bike than what you expect out of all that upgrade work. although that is the shortcut oversight that most people make when doing a modern fork swap onto a Vintage bike.

Also, fork height is a big concern. 775mm or so is where you want to be, and using different triple clamps will make the effective length even shorter by about 19 mm if I recall, because the GS upper triple is offset downwards a little bit where the forks clamp on, effectively requiring less fork length than a flat triple on top.

Most modern forks are shorter than that oh, especially upside down forks. Shorter forks will kill your cornering clearance, and make it so that you are grinding your exhaust and your stator cover at any decent lean angles when really getting into it through tight curves, which is half of the fun of owning a motorcycle!

Air-cooled Suzuki Bandit GSF 1200 forks, and Honda 2 cylinder sport bike VTR1000F Firestorm / Superhawk forks are both 775 mm length Center of axle to top of chrome tubes. Great choices. VFR750 forks may also be similar. The Bandits look the best, the Superhawk has adjustable rebound externally. Early Bandit 1200 forks with the built-in 1pc fork brace mounting tabs are valved a little stiffer for sporty riding. The later Bandit forks with the more traditional fender mounts are valved a little softer for more comfort.

Those VTR1000F Superhawk forks can bolt directly to a GS using GS 1100 GK triple clamps, but those are a little tough to come by. Then agk axle as well, but then you will still need to machine some adapters for the axle, and spacer. And then you will need to figure out braking. The twin pot brake calipers commonly used as an upgrade on GS models could be modified by cutting up and extending and welding and reconfiguring the steel bracket. These are my favorite calipers ever pretty much. You can make them look OEM to any fork with a bit of work.

Please take note that bearing swaps are sometimes needed, but All Balls has charts to help you with these conversions necessary.