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Hello
When I purchased my 2004 ST4S this year the previous owner had redone the suspension for his 200 pound weight, including new springs. I weight about 170 pounds. Is this close enough?

The bike was set up for some track days. It does have a sharp response for sure and is pretty firm and stiff. I would like to soften it a little. In sweepers it wants to not hold a perfect line. If your cruising at 70-80mph and wiggle the bars lightly the bike kinda waffles for about a second or two and settles down.

Other bikes I have had do not do that, they don’t respond that much to wiggling thebars slightly at speed. Bikes are FJR, R1200RS, R1100S, r1200GS, all stock.

Previous owner was a track instructor at circuit of the americas. So I feel he may have it set up a little too track orientation and I would like it set up for weekend rides focusing on nice sweepers.

I know very little about suspension set up. I do know when it’s in the center stand the back wheel is touching the ground slightly so back end may have been raised up.
 

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Regarding the springs, if it's a linear spring and you can adjust the preload to give you acceptable sag values then it's ok. If the springs are too stiff then even with the preload all the way off you won't get proper sag and the suspension will top out and ride rough. A heavier rider uses stiffer springs, AND track riders tend to go with stiffer springs because they don't need as much travel due to the relatively smooth surface of the track. You'll have to adjust (back off) preload and measure sag. Assuming you can adjust the preload to get you in the zone, then you can soften the ride by backing off compression and rebound damping.

There's a very good book by Andrew Trevitt called "Sportbike Suspension Tuning: How to Improve Your Motorcycle's Handling and Performance" if you want to learn the theory and fundamentals of how suspension works. Keith Code's books and videos are also useful in how they explain the relationships between the various forces on a motorcycle and the suspension's role in mitigating how these forces affect the bike's geometry.

The ST4S does have an adjustable linkage on the rear shock to vary the ride height. If the rear has been raised that will make it turn-in to corners quicker at the expense of overall stability... i.e. it will feel more "twitchy", much as you describe. It's a fine line, and the line is in different places for different riders. You can try lowering it by adjusting the linkage and see if that helps. The ST4S is really a wolf in sheep's clothing, it's a (very slightly) detuned 998 engine which actually produces more peak horsepower due to less bends in the exhaust than a stock 998. A lot of riders buy them more for the SPORT in Sport-Touring than for the Touring and adjust them for performance, either on or off the track.
 

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See if you can get numbers off of the rear springs and find out what rate you have. If it feels stiff there nothing wrong with backing off the preload front and rear to soften things up. Keep notes of adjustments so you can reverse if things get worse. Try to get sag set right front and rear with the springs you have.
 
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