Picco carbs leak guys !!!!!!! Out of 10 Picco's your going to find 3 with a split carb body that will leak and not tune...... This has been an issue with Picco for years and years..... Nobody has been quick enough to catch it tho !!!!! The seam between the composite carb body and the metal end bell is prone to leaking..you need to seal this seem with JB weld or sealant of some kind......... every Picco any of us run has this seem sealed and all our Picco's tune as easy as any other motor............ If you dont seal this seam the motors can be difficult to tune, as the airleak acts much like a Phantom leak..it will only become apparent when the motors gets fully heat soaked,,,,,,you will chase a tune forever till you seal this seem !!