2. Visually check the block for cracks and signs of corrosion. Repair stripped threads in holes. It is highly recommended to check the cylinder block for leaks in auto repair shops that have the appropriate equipment. If any defects are found, repair the unit or replace it.
3. Check for scratches and burrs on the inner surfaces of the cylinders.
4. Measure the inside diameter of the cylinder at the top (right under the flange), in the middle and lower parts parallel to the crankshaft axis. Then take measurements at the same levels, but in a direction perpendicular to the crankshaft axis. Compare the measurement results with the values specified in the manual. If there are severe burrs and scratches on the cylinder surfaces, or the ovality and taper of the cylinders exceeds the established limits, then the block must be sent to a workshop for boring and honing. After repair, pistons and rings of repair sizes will be needed.
5. If the condition of the cylinders is acceptable, the wear of the cylinder and the clearance between the cylinder and the piston do not exceed the established standards, then boring is not required. The only operation required is honing.
6. Before honing, install the crankshaft main bearing caps (without bearings), tighten the bolts to the specified torque.
7. Honing requires a special device with fine-grained grinding heads, a large amount of oil, a rag, and an electric drill. Clamp the fixture into the drill, secure the grinding heads and insert the fixture into the first cylinder. Lubricate the cylinder surface well with oil, turn on the electric drill and periodically move it up and down in the cylinder.
8. In this case, a structure of thin lines intersecting at an angle of about 60° should form on the surface of the cylinder walls.
9. Keep the cylinder surface generously lubricated at all times. Do not remove the device while rotating. After turning off the drill, continue moving it up and down until it comes to a complete stop, then squeeze the legs of the attachment with the grinding heads and remove it from the cylinder. Wipe the cylinder clean of oil and repeat the operation on the remaining cylinders. If you don't have the equipment or don't want to do the honing yourself, this operation can be done in workshops for a reasonable fee. Satisfactory results are obtained by using an emery wheel mounted on an electric drill, or even by performing the operation manually with sandpaper.
10. After honing, chamfer the top edges of the cylinder bore with a small file to prevent the rings from binding when installing the piston.
11. The entire block should be rinsed again with warm water and detergent to remove any remaining abrasive material from honing. Clean all channels with a brush and rinse with running water. After washing, dry the cylinder block and lubricate all treated surfaces with spindle oil. Before assembly, store the unit under a plastic cover.