hahaha, your kidding right???
Basic suspension 101 right there bro.

 

The stock 250 suspension isn't adjustable. (im pretty sure)

 

In my experiance with cars, the engine always took precidence over the suspension, never messed with a bike, but I can bet I'll be in for a suprise

I knew this would be embarassing []

 

Hmmm. I bet theshock is at least adjustable for static (no rider) and rider sag. See if there is an adjuster ring which will increase/decrease the amount of tension on the spring. The front forks may be minimally adjustable; do they have a small slotted screw on the top of the fork? If not, and if you plan to keep the bike, take the measurements of the forks and see if you can swap out with some that ARE adjustable. You can also do this with the shock, with some probable minor modifications like spacers, etc. Or, if you don't want to get into that, at least switch to a heavier weight fork oil, which will make the compression and rebound action a bit slower. You can "raise" the forks in the triple clamp (wouldn't go much more than 5-8mm) toput a touch more weighttoward the front.
It may all sound like a headache, but it will tighten up the bike and the ride; you'll notice the difference.

 

Well I know the rear spring/shock isn't adjustable and people swap them out for the ex500 because it's a easy swap and it's adjustable. I'll have to check out the front forks and see if there is any adjustment for them.

 

I do not know if there are preload adjusters on the 250. However, you can still change springs and fluids wt/heights. Not sure if there are dampening and compression adjusters on them, but I doubt that. Race Tech has the gold valve emulators for damping rod forks.

 

I don't think any component of our suspension is adjustable. I had a quick look yesterday and this was confirmed on http://faq.ninja250.org last night.
So I guess I'll need to spend money on tires or suspension components to get the results I want.
Since this isn't a bike I plan to keep for too long I find it difficult to justify the expense, unless I can find some nice used stuff on craigslist....