6. CYLINDER HEAD/VALVES DOWNTOWN 125i INSPECTION Remove carbon deposits from the exhaust Combustion Chamber port and combustion chamber. Be careful not to damage the cylinder head mating surface. Exhaust Port Valve /Valve guide Inspect each valve for bending, burning, scratches or abnormal stem wear. If any defects are found, replace the valve with a new one. Service limits: IN: 0.08 mm EX: 0.1 mm If the stem-to-guide clearance exceeds the service limits, replace the cylinder head is necessary. Valve spring Measure the free length of the inner and outer valve springs. 6-12