This is just a curiosity more than anything. New bikes have all kinds of emissions equipment: catalytic converters, AIS, EFI, etc., required to meet US emissions standards. We also hear about Euro Tier 2, Tier 3, etc. Yet the bikes that have been around awhile, like the DRZ400 or DR650 for example, still use carbs and as far as I know have no cats either. They are still sold as streel legal in the US. So does the emissions go with the current calendar year, or with the original bike certification date or what? Is there some kind of grandfather clause? Also does anyone know what the actual cost of emissions compliance testing costs a manufacturer for a particular model? I've always heard that certain model bikes (and cars) are not sold in the US due to this cost burden, but I've never seen a true dollar amount associated with it. Is it a flat fee? Does the size of the manufacturer matter? The number of units sold?