1996 Mercury Force 25 HP Service Manual 90-830894 895, Page 16Get this manual
6Compression check is important because an engine with low or uneven compression cannot be tuned successfully to give peak performanceIt is essential, therefore, that improper compression be corrected before proceeding with an engine tune up7Cylinder scoring: If powerhead shows any indication of overheating, such as discolored or scorched paint, visually inspect cylinders for scoring or other damage as outlined in Section "Powerhead" Serial Number Location