Service Limits & General Specifications

VALVE GUIDE CLEARANCE
Valve Stem Diameter





Measure the diameter of valve stem with a micrometer.
Standard
Intake : 5.965 - 5.980 mm (0.2348 - 0.2354 inch)
Exhaust : 5.955 - 5.970 mm (0.2344 - 0.2350 inch)

Valve Guide Inner Diameter
Measure the inner diameter of valve guide with a bore gauge.
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 - 0.053 mm (0.0008 - 0.0021 inch)
Exhaust : 0.030 - 0.063 mm (0.0012 - 0.0025 inch)
Limit
Intake :0.08 mm (0.003 inch)
Exhaust : 0.09 mm (0.004 inch)
^ If it exceeds the limit, replace valve guide and/or valve. When valve guide must be replaced, refer to "VALVE GUIDE REPLACEMENT".

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) force] or suitable tool.

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





3. Ream cylinder head valve guide hole using suitable reamer.
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. Press valve guide from camshaft side to dimensions as shown using suitable tool.
Projection H:
Intake : 10.1 - 10.3 mm (0.398 - 0.406 inch)
Exhaust : 10.0 - 10.4 mm (0.394 - 0.409 inch)

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





6. Apply reamer finish to valve guide using suitable reamer.
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 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. Refer to VALVE SEAT REPLACEMENT.

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. Refer to Valve Seat.

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 : 37.000 - 37.016 mm (1.4567 - 1.4573 inch)
Exhaust : 32.000 - 32.016 mm (1.2598 - 1.2605 inch)
^ Be sure to ream in circles concentric to the valve guide center. This will enable valve seat 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 a dry ice. Press-fit valve seats into cylinder head.

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





5. Finish valve seat to the specified dimensions. For dimensions, refer to Valve Seat using suitable tool.

CAUTION: When using a valve seat cutter, firmly grip the 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 the 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. Refer to VALVE SEAT CONTACT.

VALVE SPRING SQUARENESS





^ Set a try square along the side of valve spring and rotate valve spring. Measure the maximum clearance between the top of valve spring and try square.

CAUTION: Do not remove valve spring seat from valve spring.

Limit : 1.9 mm (0.075 inch)
^ If it exceeds the limit, replace valve spring (with valve spring seat).

VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD





^ Check valve spring pressure with valve spring seat installed at the specified spring height.

CAUTION: Do not remove valve spring seat from valve spring.





Standard





CYLINDER HEAD