Engine Block and Piston Inspection

1.Remove the crankshaft and pistons.

2.Check the piston for distortion or cracks.

3.Measure the piston diameter at a point 14 mm ( 0.6 in.) from the bottom of the skirt. There are two standard-size pistons (A and B). The letter is stamped on the top of the piston. Letters are also stamped on the engine block as cylinder bore sizes.

Piston Diameter
Standard (New): 
A: 84.950-84.980 mm (3.3445-3.3457 in.) 
B: 84.940-84.970 mm (3.3441-3.3453 in.) 

Service Limit: 
A: 84.920 mm (3.3433 in.) 
B: 84.910 mm (3.3429 in.) 

Oversize Piston Diameter 
0.25: 85.20-85.23 mm (3.354-3.356 in.) 



4.Measure wear in direction X and Y at a point 50 mm (2.0 in.) from the top of the engine block in each cylinder as shown. If measurements in any cylinder are beyond the Oversize Bore, replace the engine block/lower block assembly. If the engine block is to be rebored, refer to 7 after reboring.

Cylinder Bore Size 
Standard (New): 
A or I (X): 84.997-85.027 mm
(3.3463-3.3475 in.)
A or I (Y): 84.986-85.016 mm
(3.3459-3.3471 in.)
B or II (X): 84.987-85.017 mm
(3.3459-3.3471 in.)
B or II (Y): 84.976-85.006 mm
(3.3455-3.3467 in.)
Service Limit: 85.050 mm (3.3484 in.) 

Oversize Piston Diameter+0.050-0.070 mm
(0.0020-0.0028 in.)


5.Scored or scratched cylinder bores must be honed.

6.Check the top of the engine 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: 0.07 mm (0.003 in.) 



7.Calculate the difference between the cylinder bore diameter (direction Y) 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): 0.006-0.066 mm
(0.0002-0.0026 in.)
Service Limit: 0.066 mm (0.0026 in.) 

Oversize: 0.050-0.070 mm
(0.0020-0.0028 in.)
Oversize Service Limit: 
 0.070 mm (0.0028 in.)