2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 82Get this manual
CHANGING THE ENGINE OIL ADJUSTING THE CLUTCH CABLE 14.Check: engine oil pressure
aSlightly loosen the oil gallery bolt bStart the engine and keep it idling until engine oil starts to seep from the oil gallery boltIf no engine oil comes out after one minute, turn the engine off so that it will not seizecCheck the engine oil passages, the oil filter element and the oil pump for damage or leakageRefer to "OIL PUMP AND BLANCER WEIGHT GEAR" in chapter 4dStart the engine after solving the problem(s) and check the engine oil pressure againeTighten the oil gallery bolt to specification7 Nm (0.7 mkg, 5.2 ftlb)