Among the motorcycles with product scale of 1:10, which of them is the most ordered by American customers?
motorcycle is a product line; American is a nationality of country = 'USA';
SELECT T1.productName FROM products AS T1 INNER JOIN orderdetails AS T2 ON T1.productCode = T2.productCode INNER JOIN orders AS T3 ON T2.orderNumber = T3.orderNumber INNER JOIN customers AS T4 ON T3.customerNumber = T4.customerNumber WHERE T1.productLine = 'Motorcycles' AND T1.productScale = '1:10' AND T4.country = 'USA' GROUP BY T1.productName ORDER BY SUM(T2.quantityOrdered) DESC LIMIT 1