2007 Johnson 2 HP 4-Stroke Service Manual, Page 91Get this manual
POWERHEAD CYLINDERCRANKCASEPISTON Measure the cylinder bore in the thrust and axial directions at the three position depthsCylinder bore: 1.8898 to 1.8904 in(48.000 to 48.015 mm) Piston skirt diameter: 1.8888 to 1.8894 in(47.975 to 47.990 mm) Oversize piston and piston rings are marked as shownPiston Oversize 0.50 mm
006075 006076
I.DMark 50
Check for the following: Difference between the measurements at the three positions (taper) Difference between the thrust and axial measurements (out-of-round)Oversize Piston I.DMark
First and Second Ring Oversize 0.50 mm I.DMark 50
Cylinder bore wear (difference): Service limit 0.0039 in(0.100 mm) If the wear (difference) exceeds the service limit, rebore or replace the cylinderTo check the piston to cylinder clearance, measure the following items: Cylinder bore at 20 mm elevation from the gasket surface at right angle to the crankshaft pin Piston skirt diameter at mm elevation from the skirt endPiston to cylinder clearance: Standard 0.0007 to 0.0013 in(0.018 to 0.033 mm) Service limit 0.0039 in(0.100 mm) If the clearance exceeds the service limit, replace the piston andor the cylinder, or rebore cylinder