Put it this way, your engine may be running good but it's not running optimally. Ideally, each engine cycle is going to burn X amount of the fuel/air mixture pulled through the carbs. Your engine is pulling X+Y probably because the main jets are too big. X will always get burned up in the engine no matter what because that how much it is designed to burn in a given engine cycle. Y is getting burned up in the exhaust or just getting spewed out on the road, person behind you, whatever. This extra fuel burning up in the exhaust can contribute to pipes blueing faster and while it looks cool, it's also lost fuel. You wouldn't ride around with a hole in your fuel line, why spit unburnt fuel out of the exhaust? As an engineer I want my engine running as efficiently as possible and as a tightwad I want to use every bit of fuel I buy to go towards running the engine and not entertaining the folks behind me. OK, I'll get off my
for now.
First thing I would do is check out what size the main jets are and maybe drop them down a few sizes (i.e. take 135 jets down to 130 and check the plugs). You might even get better fuel mileage with the correct jets.
