I have read the article about 650L carb mods by Dave and Brian. I understand why to drill out the slide, and why to raise the needle. But my question is about jetting and the air mixture screw. I have a full white brothers E-Series exhaust and a K&N filter. When I go to re-jet does a 160 main and a 55s pilot sound right?. Also what do you look for with the air screw? Do you check the spark plug? Is it in the performance of the bike? Or maybe the idle? And can you damage the engine if it is a little off? And finally how do you test all these? Can someone with experience with these modifications please give me some advice. It would be greatly appreciated.