Procedures

NOTE:
^ Numbers in parentheses ( ) indicate a component or tool in the associated illustration.
^ Only face cylinder head contact surface if porous or damaged points exist.
^ Minor differences in the flatness in the longitudinal direction should not be reworked.
^ These even themselves out when the cylinder head is tightened.

PROCEDURE
1. Remove valves. [1][2]Procedures
2. Prechambers removed. Service and Repair
3. Inspect cylinder head contact surface for flatness, porous or damaged points
4. Inspect hardness of cylinder head contact surface, refer to Cylinder Head Contact Surface. Testing and Inspection

NOTE:
^ If the cylinder head has been subjected to excessive heat, this can result in a change in the microstructure.
^ Machining them will only produces a tight seal of cylinder head/cylinder head gasket/crankcase if certain minimum hardness is achieved.

5. Measure height of cylinder head (check dimension H)
- Note reading obtained
6. Face cylinder head contact surface noting the following information and specifications:
- The stock removal at the cylinder head and at the crankcase together should not be more than 0.5 mm.
- If the Cylinder Block (crankcase) has already been machined, the maximum stock removal at the cylinder head contact surface should not be more than 0.3 mm.
- The camshaft housing must not be machined otherwise the basic bores of the camshaft bearings will be altered.
- Test data of cylinder head:
Height of cylinder head (H) without camshaft housing
When new: 126.85-127.15 mm
Wear limit after machining: 126.8 mm
Unevenness of contact surface in longitudinal, transverse direction ≤0.04 mm
Peak-to-valley height: 0.006 mm
Distance (a) for new valves and new valve seat rings
Exhaust valve: 1.300-1.700 mm
Inlet valve: 1.300-1.700 mm
Distance from valve stem end to base of camshaft bearing (T): 23.700-24.200 mm
Hardness of cylinder head contact surface in area of sealing bead of cylinder head gasket: >70
7. Once again measure height of cylinder head (check dimension H)
- Measure stock removal.
8. Rework valve seats according to the stock removal at the cylinder head, refer to Refinish. Service and Repair
9. Measure distance from valve stem end to the base of the camshaft bearing
- Check dimension (T), as follows:
Insert diameter 5 mm round bar into the base of the camshaft bearing for this purpose and measure dimension "T".
or:





- Check dimension (a) see illustration above
Measuring amount by which valve stands back

NOTE:
^ If the measurement obtained is less than dimension "T" or "a", it is no longer possible to achieve correct valve clearance compensation; replace valve seat ring or cylinder head as appropriate
^ Replace valve seat ring. Service and Repair

10. Install in the reverse order