Block and Piston Inspection

1. Remove the crankshaft and pistons (see CRANKSHAFT AND PISTON REMOVAL ).
2. Check the piston for distortion or cracks.
3. Measure the piston diameter at a point 13 mm (0.5 in) from the bottom of the skirt. There are two standard-size pistons (No Letter or A, and B). The letter is stamped on the top of the piston. Letters are also stamped on the block as cylinder bore sizes.

   Piston Diameter 

   Standard (New): 

   No Letter (or A): 86.980-86.990 mm (3.4244-3.4248 in) 

   B: 86.970-86.980 mm (3.4240-3.4244 in) 

   Service Limit: 

   No Letter (or A): 86.930 mm (3.4224 in) 

   B: 86.920 mm (3.4220 in) 

   Oversize Piston Diameter 

   0.25: 87.230-87.240 mm (3.4342-3.4346 in) 

   Fig 1: Measuring Piston Diameter From Bottom Of Skirt

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
4. Measure the wear and taper in direction X and Y at three levels inside each cylinder as shown. If the measurements in any cylinder are beyond the Oversize Bore Service Limit, replace the block. If the block is being rebored, refer to step 7 after reboring.

   Cylinder Bore Size 

   Standard (New): 

   A or I: 87.010-87.020 mm (3.4256-3.4260 in) 

   B or II: 87.000-87.010 mm (3.4252-3.4256 in) 

   Service Limit: 87.070 mm (3.4279 in) 

   Oversize Bore 

   0.25: 87.250-87.260 mm (3.4350-3.4354 in) 

   Reboring Limit: 0.25 mm (0.010 in) max. 

   Bore Taper 

   Limit: (Difference between first and third measurement) 0.05 mm (0.002 in) 

   Fig 2: Identifying Cylinder Bore Size Dimension

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
5. Scored or scratched cylinder bores must be honed.
6. Check the top of the block for warpage. Measure along the edges, and across the center as shown.

   Engine Block Warpage 

   Standard (New): 0.07 mm (0.003 in) max. 

   Service Limit: 0.10 mm (0.004 in) 

   Fig 3: Precaution For Engine Block Warpage

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
   Fig 4: Checking Engine Block Warpage

   Courtesy of AMERICAN HONDA MOTOR CO., INC.
7. Calculate the difference between the cylinder bore diameter and the piston diameter. If the clearance is near or exceeds the service limit, inspect the piston and cylinder bore for excessive wear.

Piston-to-Cylinder Bore Clearance 

Standard (New): 0.020-0.040 mm (0.0008-0.0016 in) 

Service Limit: 0.05 mm (0.002 in) 

Fig 5: Identifying Piston-To-Cylinder Bore Clearance

Courtesy of AMERICAN HONDA MOTOR CO., INC.