If your looking for (HP) value for money spent don't stop at 685cc. For little more you can go with 705 or if they make a bigger piston go for it. The DR 650 is being bored out to 790cc with great reliability and the extra torque is worth a lot. While you have it apart clean up the ports for a good gain in mid-range to top end for no money at all. I spent a couple hours in the head of my DR (my first ever 4 stroke porting effort- although I used to port my (2 stroke mx bikes) and it really felt better on the top end with nothing lost on the bottom. Cost was zero as I just cleaned up the passageways- no polishing involved. The next focus is the cam if you still have cash left. Last- look into larger valves, but this is a big project on these heads. Next time I take my DR apart I'm going to simply bore out the valve seat material using the same valves. This will open up the size of the port into the cylinder maybe just 5% in diameter but the overall effect will be greater because of the increase in volume through that circumference. You may have to increase the cooling capacity as the determining factor to radiator size is basically horsepower and not cc"s. I saw an article years ago where a KLR owner installed two radiators if I remember correctly. Most will tell you to upgrade to a different bike especially since the new Husky is only $500 more than the new KLR, but one advantage to the existing KLR is you can add power as your budget allows. After these increases you would of course want to upgrade the exhaust to take advantage of the other effects.