I'll say this right off so no one is confused.
TIGHTENING THE CASE BOLTS WILL NOT FIX 97 S CLUTCH COVER OIL LEAKS.
ok, so quit honkin down on them and read this.
If you don't know, TL clutch covers are made out of plastic, three layer sandwich, but none the less, plastic. Plastic is much softer then aluminum, steel, magnesium, etc.
So the bright guys at Suzuki put steel spacers in the plastic where the mounting bolts would go through to keep wrench heads from crushing the be-jesus out of the soft (read that cheap to manufacture) plastic clutch cover
alright, so far, so good.... the cover is mounted on the bike, the flange head bolts are run through the spacer lined mounting holes and tightened.... pushing the O-ring into the grove and against the engine case. Everything seales up nice and tight..... until you heat the plastic up a few hundred times, it gets soft and the plastic under the bolt squishes..... the bolt is now sitting against the spacer.
the case can move on the spacer, I punched them out with a pencil, just putting it in the hole and pushing. They are press fit. So the bolt is now pressing against spacer and the squished plastic cover can sort of float around on the spacers. Moving in and out as heat and case pressure changes and every time it moves it squishes the plastic even more, making it more loose.... AND MORE LEAKY
Ok, so this is why tightening the mount bolts doesn't work. YOU ARE SIMPLY TIGHTENING THE BOLTS AGAINST THE SPACERS. YOU ARE NOT ACTUALLY PRESSING THE CLUTCH COVER ANY TIGHTER AGAINST THE ENGINE CASE.
The newer replacement cases are actually the same size (with a few changes in the height of the spacers) but have a "T" shaped spacer that spreads the pressure of the mounting bolt out over more area of the plastic clutch cover. The "T" also prevents the cover from 'floating' around on the spacer shaft.
So what can you do to your 97 S cover to make it stop leaking. Or do a little pre-emptive strike to stop it before it starts.
Two easy steps.... Remove the spacers (a punch and hammer, or a pencil and a tough palm of the hand) and then shorten them up just a little bit. I ran them through my lathe but you can pass a file over them, sand them on some course sand paper.... invent your own way to take off about 1/32nd of an inch (thats half a millimeter for you metric types) of spacer lenght.
Then get some washers and put them on as you mount the bolts in place (make your own "T" spacer)
I would replace the O-ring and give it a little oil bath before installing just to be on the safe side if you have had a chronic oil leak problem.
there you have it, how to fix your leaky 97 S clutch cover.