Piston to Cylinder Bore Clearance
PISTON TO CYLINDER BORE CLEARANCEInner Diameter of Cylinder Bore
^ Using a bore gauge, measure cylinder bore for wear, out-of-round and taper at 6 different points on each cylinder. (X and Y directions at A, B and C). The Y axis is in the longitudinal direction of the engine.
NOTE: When determining cylinder bore grade, measure cylinder bore at B position.
Cylinder bore inner diameter
Grade No.1: 89.000 - 89.010 mm (3 5039 - 3.5043 inch)
Grade No. 2: 89.010 - 89.020 mm (3 5043 - 3.5047 inch)
Grade No. 3: 89.020 - 89.030 mm (3.5047 - 3.5051 inch)
Wear limit: 0.2 mm (0.008 inch)
Out-of-round 0.015 mm (0.0006 inch) (difference between, X - Y):
Taper limit (difference 0.01 mm (0.0004 inch) between, C - A):
^ If the measured value rebore exceeds the limit, or if there are scratches and/or seizure on the cylinder inner wall, hone the inner wall.
^ An oversize piston is provided. When using an oversize piston, rebore the cylinder so that the clearance of the piston cylinder satisfies the standard.
Piston oversize (OS)
Clearance: 0.2 mm (0.008 inch)
Diameter: 89.180 - 89.210 mm (3.5110 - 3.5122 inch)
Outer Diameter of Piston
^ Measure piston skirt diameter (A).
Piston skirt diameter
Grade No.1: 88.980 - 88.990 mm (3.5031 - 3.5035 inch)
Grade No. 2: 88.990 - 89.000 mm (3.5035 - 3.5039 inch)
Grade No. 3: 89.000 - 89.010 mm (3.5039 - 3.5043 inch)
Oversize 0.20 mm (0.0079 inch) clearance
^ Measure point (a) (distance from the top): 42 mm (1.65 inch)
Piston to Cylinder Bore Clearance
^ Calculate by outer diameter of piston skirt and inner diameter of cylinder (direction X, position B). (Clearance) = (Inner diameter of cylinder) - (Outer diameter of piston skirt).
Standard: 0.010 - 0.030 mm (0.0004 - 0.0012 inch)
Limit: 0.08 mm (0.0031 inch)
^ If it exceeds the limit, replace piston/piston pin assembly.
Reboring Cylinder Bore
1. Cylinder bore size is determined by adding piston-to-bore clearance to piston diameter A.
Rebored size calculation: D = A + B - C
D: Bored diameter
A: Piston diameter as measured
B: Piston-to-bore clearance (standard value)
C: Honing allowance 0.02 mm (0.0008 inch)
2. Install main bearing caps, and tighten to the specified torque. Otherwise, cylinder bores may be distorted in final assembly.
3. Cut cylinder bores.
NOTE: When any cylinder needs boring, all other cylinders must also be bored.
CAUTION: Do not cut too much out of cylinder bore at a time. Cut only 0.05 mm (0.0020 inch) or so in diameter at a time.
4. Hone cylinders to obtain specified piston-to-bore clearance.
5. Measure finished cylinder bore for out-of-round and taper.
NOTE: Measurement should be done after cylinder bore cools down.