oh, forgot how many times you're sprocket falls off. So once I only had two of four nuts loosely holding the sprocket on... I was working on the bike and decided to test it, well I never went back to check the sprocket. Luckily the wheel hub has a large enough part of the tube sticking out to hold the sprocket on... the bolts didn't fall out because the force pulling at the sprocket. oops
I imagine engine mods can't be too good for mileage either once you get into the serious stuff. Each time you reject to a bigger jet you're adding more fuel. Which means more gas used "per hour".