A good starting point for sag is based on a rule of thumb. It is not gospel. As you get faster your sag likely will not look anything like it does now. Racers do not go by sag numbers or every bike would have a book that has numbers for every rider weight. Actually, I bet most racers have no idea what their sag is.
Since you're riding a 675 we can rule out bad suspension (unless it's faulty). Harshness could be old oil, bad setup of rebound and compression and/or sag, bad tires, messed up geometry, etc. Also, remember sag sets a preload on the spring and in turn changes ride height, which is why when you get sag you need to be sure the front and rear of the bike still is within heights that keep the proper geometry. Sometimes you will need to set the fork in the triple to another position to have the correct suspension travel and still have good geometry. Sag(set using spring preload) does not change the spring rate. 0.9 is a 0.9 no matter what the sag is set to.
Sag is set primarily to give you maximum suspension travel. The rule of thumb is usually about 2/3 left of suspension travel when you are sitting on the bike with full gear. Since most sport bikes have about the same length fork travel, the sag number is born.
I suggest you put a ziptie around one of the forks, and if you can, on the shaft of the rear spring. You generally want the fork/spring to compress as much as possible on your hardest braking without bottoming, but getting close. Not panic braking but controlled braking.
Most people setup their bikes way too stiff because that's what most people think high performance means. Hence why so many modified cars have such bad suspension setups, but that's another story for another day.
Also check the rebound and compression of your forks and rear shock. Keep a notebook and write down all settings. Also note how the bike feels and how the tires look. Make one change at a time and note the difference. You will learn pretty quickly how to adjust the suspension based on feel and tire wear.
So on my last couple of track days of the season Iíve done a couple things you suggested. Zip tied a fork and the shock. Ive also started a chart of suspension adjustments so to keep track of what Iím doing and making notes of how I think it handles. I also got to ride on a different track that is much smoother and probably more realistic of what a standard track is like. The one spot on the old track that generated me to start this thread is really my only complaint and it was only when running in that clubs direction. (We have 2 clubs that each run the same track in a different direction than the other). Either way I though Iíd post a pic of the fork zip tie and see what is thought about it. It seems a little low to me but Iím definitely not bottoming and this represents my fastest time of the day.
Despite that one spot on the one track, this bike seems to handle excellently and gives me the most confidence of any bike Iíve ridden. HOWEVER, I did spend some time on the track this past summer with a cheap 2003 ZX6R track bike
thinking this may be the way to go. It is a full non-street legal track bike with Ohlins shock, Ohlins steering dampener, Race Tech forks, slicks etc. The springs were a little soft for me but I wasnít bottoming. In hindsight I think the geometry on this bike is way off. The Ohlins certainly didnít belong on this bike but I think it was just jammed in there. Anyway, I crashed the bike at 40 MPH, low sided on a long sweeper corner and when the bike hit the dirt it high sided- due to the front tire not sticking. Scared the crap out of me and now I feel like Iím back at infant stage regarding the track. The spot I crashed on had a slight pavement change (a patch), I was at lean, on a cold day, early in the session with presumably cold tires that were slicks. My instructors said those slicks were about the worst think someone at my entry level could have on a bike especially on a cold day due to how slicks are meant to dissipate heat (for a much faster rider) and DOT tires are meant to retain heat ( for someone like me). This whole event has me nervous to even push the Daytona again, subconsciously wondering if the Daytonaís front tire will stick. But I need to get past it. Hopefully little by little I can eek my speed back to where I was. The Daytona inspired so much confidence in me on the smooth track, I want to get back to that feeling again.
Anyway, the shocks zip tie looks similar to this, but maybe not down quite as much.