just found this http://www.thegsresources.com/_forum/showthread.php?170903-GS500-front-sprocket-almost-killed-me-last-night

something i've been thinking about and perhaps its not as sophisticated as i had planned but the same principle, he's welded a bolt onto the countershaft so he can bolt down the front sprocket. i had planned on drilling and tapping into the shaft so i could get a spacer made up i could bolt onto the shaft. similar idea but a lot less work. just have no idea why suzuki thought it was an acceptable way to mount a sprocket.

credit to 'wera racer' on the gs resources 

might be of use to someone else 

I am thinking of machining a collar with a grub screw to clamp the shaft with a recess for the circlip. That should stop it coming off and not weight much. The force sideways will be pretty small.

Quote from: gregjet on July 23, 2016, 02:52:49 PM
I am thinking of machining a collar with a grub screw to clamp the shaft with a recess for the circlip. That should stop it coming off and not weight much. The force sideways will be pretty small.

Sounds good Greg. Part of my issue is that there's rotational play on the countershaft and I need means of keeping the sprocket fixed to eliminate play. A fair few gs's suffer from it.

Had another look and maybe the collar could go on the back easier. The sprockets I bought are easily got and cheap JT's and come with 2 sets of 2 holes. Perfect for bolting onto the collar ( I would only use 2. More width for the grub screw then.

Quote from: gregjet on July 28, 2016, 01:42:47 PM
Had another look and maybe the collar could go on the back easier. The sprockets I bought are easily got and cheap JT's and come with 2 sets of 2 holes. Perfect for bolting onto the collar ( I would only use 2. More width for the grub screw then.

thats a thought, i know the ones you're on about. i'm having to space both sprockets out but about 3mm for tyre clearance on a wheel swap so im kind of hoping its enough to pull the sprocket out of the worn spot just enough for it so sit steady. still going to have to come up with means of getting it completely secure so its not just another issue in the future right enough. food for thought anyway, really interested to see what you come up with.

Just a thought again, Has anyone managed to get that spacer behind the CS sprocket off. I tried a bit but didn't want to damage the bearing. Is it possible without splitting the cases and taking out the output shaft?
I could then make a bigger diameter spacer to screw the CSs to. Maybe even put a rubber/ureathane sheet between to quieten the chain/sprocket noise.