Tohatsu 4 Stroke MFS 2/2.5/3.5A Outboards Service Manual, Page 27Get this manual
Service Data 5.Maintenance Data
Description Item Build up of carbon in combustion chamber Deposits in water jacket Cylinder Block Cylinder Head Wear of boreUse cylinder gauge to measure inner diameter55.00mm (2.1654in) Seizure, cylinder liner damage, or wear Taper Out-of-roundness Outer Diameter Measure outer diameter at 7mm (0.28in) above lower end of piston skirt (at right angle to piston pin)Piston Clearance Carbon build up on piston crown and in ring grooves Piston Scratch on the sliding surface Top Ring0.040.08mm (0.00160.0031in) Measure side clearance between piston ring and ring grooveSecond Ring0.030.07mm (0.00120.0028in) Oil Ring0.050.15mm (0.00200.0059in) Measure piston pin hole diameterPiston Pin Outer Diameter Ring End Gap Piston Ring Top Ring Second Ring Oil Ring Small End Inner Diameter Connecting Rod Big End Oil Clearance Big End Side Clearance Big End Inner Diameter Crank pin outer diameter Crankshaft Crankshaft roundnessUse blocks to support crankshaft at bearings of both endsValve Clearance Valve Stem Outer Diameter Intake Valve Exhaust Valve Valve Guide Inner Diameter Clearance between valve guide and valve stem Width of contact with valve seat Valve Spring Free Length Cam Height (Both IN and EX) Cam Shaft Journal Outer Diameter Cam Shaft Swing Engine Block Compression Pressure (Reference) at 500rmin 1.13MPa (164psi) 11.5kgf NoteMeasurement of ring end gapIf ring gauge is not available, use cylinder bore top or bottom where the wear is smallTop Ring0.150.30mm (0.00590.0118in) Second Ring0.300.45mm (0.01180.0177in) Oil Ring0.200.70mm (0.00790.0276in) 14.01mm (0.5516in) 0.0150.041mm (0.000590.00161in) 0.100.25mm (0.00390.0098in) 20.010mm (0.78780in) 19.98mm (0.7866in) Less than 0.05mm (0.0020in) at both ends