Honda BF50 (5HP) BF5A Outboard Motors Shop Manual., Page 43Get this manual
VALVE GUIDE I.D' NOTE: Ream the valve guides remove any carbon deposits before measuring
Measure and record each valve guide I.DSTANDARD 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
Subject each valve stem O.Dfrom the corresponding guide I.Dto obtain the stern-toquide clearance
STANDARD
SERVICE LIMIT
0.020-0.044 mm (O.WO8-0.0017 in) 0.0604.087 mm
0.07 mm (0.003 in
0.1 rnm (0.006 in)
(0.0024-0.0034 in)
If the stem-to-guideclearance exceeds the service limit, determine if the new guide with standard dimensions would bring the clearance within toleranceI so, replace any guide necessary and ream to fitIf the stem-to-guide clearance exceeds the service limit with new guides, replace the valve as well