Not to put too fine a point on it, but simply jacking up the preload is a tiny band-aid at best. Preload has a specifc place (with some variations to taste) it should be set for each rider. The SV's suspension - particularly the front - is lacking in both spring rate and damping.
Taken from SuperStreetBike.com:
Proper sag is important because a suspension unit needs a certain amount of room within its travel to work properly. If you have too little sag, your bike will be prone to topping out the suspension as it extends to its limit. Similarly, too much sag could allow you to exper-ience the unpleasant jolt of bottoming out. Your bike's sag is broken into two categories: "static sag," the distance your bike compresses its suspension from fully extended when you climb on board; and "free sag," the distance your bike settles from full extension under its own weight.