there really isn't anything else worth doing that you could do, any other motor mods are going to be expensive and require rejetting and tuning... depending on what the previous owner didn't change recently, i'd consentrate on some good maintainance, that will make it perform alot better, new air filter, new spark plugs, fuel filter if it has one, tires, chain and sprockets(if you want more "power" you could go up some teeth on the rear sprocket, it doesn't actually give you power, but its the cheapest way to make it faster by lowering the gearing), oil change, valve adjustment, carb cleaning, etc., new fork seals and some good fork oil, and set up the suspension for your weight

but as far as motor mods i think there isnt' anything left that would be worth your money