19.1. Rocker arms of engines on which it is not necessary to adjust valve clearances look like this (indicated by arrows) - they do not have adjusting screws
1. Valve clearances should be adjusted at regular intervals when the engine has reached normal operating temperature. On some models, valve clearances are not adjustable. These models do not have adjusting screws (19.1) on the valves.
2. Remove the air filter and valve cover.
3. Set the piston of cylinder N1 to the TDC position at the moment of the compression stroke. In this position, the rocker arms of the first cylinder should move freely.
19.4. When the piston of cylinder N1 is at TDC, adjust the clearances of the valves marked with the letter A - when the piston of cylinder N4 is at TDC, adjust the clearances of the valves marked with the letter B
4. In this position the valves marked with the letter A (and the injection valves located near the inlet valves) can be checked and adjusted. Always check and adjust the injection valve clearances first (19.4).
5. The adjusting screws of the intake and injection valves are located on the rocker arms. Loosen the adjusting screw of the intake valve two full turns, then loosen the lock nut on the adjusting screw of the injection valve.
19.6. When removing the feeler gauge from the gap between the valve and the adjusting screw, a slight resistance should be felt
6. Insert the feeler gauge between the injection valve stem and the adjusting screw and carefully tighten the screw until the feeler gauge is lightly pressed against the valve by the screw (19.6).
7. Since the injection valve spring is relatively weak, be careful not to open the valve.
19.8. To prevent the adjusting screw from turning when tightening the lock nut, hold it with a wrench
8. Then check and adjust the clearances of the intake valves, and then the clearances of the exhaust valves (19.8).
9. Set the piston of cylinder N4 to the TDC position during the compression stroke and adjust the valve clearances marked with the letter B (19.4).
10. After completing the adjustment, reinstall the valve cover and air filter.