Sorry but a motor wants what it wants and this one wanted a little more fuel. I been rebuilding carbs and jetting them for street bikes and atv's for 15 years and trust me this carb ran this way from new. The drill bits are made for fine tuning and been used for years. I do agree if in spec they run good but that spec is so close to lean all it takes is one very small change. Sorry but I have been jetting carbs for many years and every location is different. Sea level to 5000ft and weather conditions all play a roll. Small engine department at work fine tunes these everyday and 50% of the time sizing jets is part of the tuning. Yes cleaning these jets with these bits will solve the problem sometimes but not always. Just because it's not talked about doesn't mean it's not a common practice.