Honda BF50 (5HP), BF5A Outboard Motors Shop Manual 2014, Page 45Get this manual
BF50BF5A VALVE GUIDE 1.0NOTE: Ream the valve guides to remove any carbon deposits before measuringMeasure and record each valve guide 1.0STANDARD IN EX 5.50 mm (0.217 In) 5.50 mm (0.217 in) SERVICE LIMIT 5.54 mm (0.218 in) 5.57 mm (0.219 in)
Replace the guides if they are over the service limit
VALVE GUIDE-TO-STEM CLEARANCE
Subtract each valve stem 0.0from the corresponding guide 1.0to obtain the stemto-guide clearanceSTANDARD IN EX 0.020-0.044 mm (0:0008-0.0017 in) 0.060-0.087 mm (0.0024-0.0034 in) SERVICE LIMIT 0.07 mm (0.003 in) 0.15 mm (0.006 in)
If the stem-toguide clearance exceeds the service limit, determine if the new guide with standard dimensions would bring the clearance within toleranceIf so, replace any guide as necessary and ream to fitIf the stemto-guide clearance exceeds the service limit with new guides, replace the valves as wellNOTE: Recondition the valve seats whenever the valve guides are replaced
cVALVE GUIDE REPLACEMENT