Service Limits & General Specifications

Inspection After Disassembly

VALVE DIMENSIONS





^ Check the dimensions of each valve.
^ If the dimensions are out of the standard, replace valve and check the valve seat contact.

VALVE GUIDE CLEARANCE
Valve Stem Diameter





Measure the diameter of valve stem with micrometer.
Standard
Intake: 5.972 - 5.980 mm (0.2351 - 0.2354 inch)
Exhaust: 5.962 - 5.970 mm (0.2347 - 0.2350 inch)

Valve Guide Inner Diameter
Measure the inner diameter of valve guide with inside micrometer.
Standard
Intake and Exhaust: 6.000 - 6.018 mm (0.2362 - 0.2369 inch)

Valve Guide Clearance
(Valve guide clearance) = (Valve guide inner diameter) - (Valve stem diameter).
Valve guide clearance:
Standard
Intake: 0.020 - 0.046 mm (0.0008 - 0.0018 inch)
Exhaust: 0.030 - 0.056 mm (0.0012 - 0.0022 inch)
Limit
Intake: 0.08 mm (0.003 inch)
Exhaust: 0.1 mm (0.004 inch)

^ If the calculated value exceeds the limit, replace valve and/or valve guide.

VALVE GUIDE REPLACEMENT





When valve guide is removed, replace with oversized [0.2 mm (0.008 inch)] valve guide.
1. To remove valve guide, heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.





2. Drive out valve guide with a press [under a 20 kN (2 ton, 2.2 US ton, 2.0 Imp ton) pressure] or hammer and valve guide drift (commercial service tool).

CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





3. Using valve guide reamer (commercial service tool), ream cylinder head valve guide hole.
Valve guide hole diameter (for service parts):
Intake and exhaust: 10.175 - 10.196 mm (0.4006 - 0.4014 inch)





4. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.





5. Using valve guide drift (commercial service tool), press valve guide from camshaft side to the dimensions as in the figure.

CAUTION: Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





6. Using valve guide reamer (commercial service tool); apply reamer finish to valve guide.
Standard:
Intake and exhaust: 6.000 - 6.018 mm (0.2362 - 0.2369 inch)

VALVE SEAT CONTACT





^ After confirming that the dimensions of valve guides and valves are within the specifications, perform this procedure.
^ Apply Prussian blue (or white lead) onto contacting surface of valve seat to check the condition of the valve contact on the surface.
^ Check if the contact area band is continuous all around the circumference.
^ If not, grind to adjust valve fitting and check again. If the contacting surface still has NG conditions even after the re-check, replace valve seat.

VALVE SEAT REPLACEMENT
When valve seat is removed, replace with oversized [0.5 mm (0.020 inch)] valve seat.
1. Bore out old seat until it collapses. Boring should not continue beyond the bottom face of the seat recess in cylinder head. Set the machine depth stop to ensure this.

CAUTION: Prevent to scratch cylinder head by excessive boring.





2. Ream cylinder head recess diameter for service valve seat.
Oversize [0.5 mm (0.020 inch)]
Intake: 37.500 - 37.516 mm (1.4764 - 1.4770 inch)
Exhaust: 32.700 - 32.716 mm (1.2874 - 1.2880 inch)
Be sure to ream in circles concentric to valve guide center. This will enable valve to fit correctly.





3. Heat cylinder head to 110 to 130°C (230 to 266°F) by soaking in heated oil.
4. Provide valve seats cooled well with dry ice. Force fit valve seat into cylinder head.

CAUTION:
^ Avoid directly touching cold valve seats.
^ Cylinder head contains heat. When working, wear protective equipment to avoid getting burned.





5. Using valve seat cutter set (commercial service tool) or valve seat grinder, finish seat to the specified dimensions.

CAUTION: When using valve seat cutter, firmly grip cutter handle with both hands. Then, press on the contacting surface all around the circumference to cut in a single drive. Improper pressure on with cutter or cutting many different times may result in stage valve seat.

6. Using compound, grind to adjust valve fitting.
7. Check again for normal contact.

VALVE SPRING SQUARENESS





^ Set try square along the side of valve spring and rotate spring. Measure the maximum clearance between the top face of spring and try square.
Limit: 2.0 mm (0.079 inch)
^ If it exceeds the limit, replace valve spring.

VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD





^ Check valve spring pressure at the specified spring height.
Standard:
Intake and exhaust
Free height: 46.35 - 46.85 mm (1.8247 - 1.8444 inch)
Installation height: 33.8 mm (1.331 inch)
Installation load: 165 - 189 N (16.8 - 19.3 kg, 37 - 42 lb)
Height during valve open: 24.4 mm (0.961 inch)
Load with valve open: 290 - 330 N (29.6 - 33.7 kg, 65 - 74 lb)
^ If the installation load or load with valve open is out of the standard, replace valve spring.

CYLINDER HEAD:

CYLINDER HEAD