Beijing's so-called mini stimulus seems to be having not-so-mini results. For the second month in a row, an early reading shows factory sentiment rising to its highest level in 18 months. The HSBC/Markit Flash China Manufacturing PMI rose to 52 in July, well above forecasts and above the 50 line that separates expansion from contraction. The sub-index for new orders—a gauge of demand at home and abroad—also hit an 18-month high of 53.7. But can that momentum continue?