Engine body Fitting of cylinder head Fig. 27. Clearance rocker - rocker shaft Fig. 28. Fitting of valve stem seals 5. Check that the rocker bearing surfaces are not out- of-round worn. 1. Press down new valve stem steals on the valve guides. Calculate the clearance between the rocker and shaft. The clearance must not exceed 0.2 mm (.0078 in). Note: MD2030 and MD2040 have different seals for the guides for the inlet and outlet valves. Check that the ball pin's spherical part is not defor- med or worn. The threads should be undamaged on the pin and lock nut. The locknut should be in good condition. The mating sphere of the rockers (against the val- ve) must not be unevenly worn or concave.
Adjust- ment for minor wear can be made in a grinding machine. C c Note: MD2O10-2030. A new type of rocker (includ- i ng valve cap) has been introduced as from engine number: MD2010: 5101202984 MD2020: 5101308898 M D2030: 5101465653 Only the new type of rocker is available as a spare part. If one or several of the older type of rocker need to be replaced, all the rockers must be re- placed at once, and valve caps installed on the valve stems. 00 2 Fig. 29. Fitting of valves 1. Valve lock 3. Valve spring 2. Valve spring retainer 5. Valve cap* 4. Valve * MD2040 and later versions of MD2O10, 2020, 2030 2. The valves should be fitted in the correct order.
Oil i n the valve spindles and fit the valve in its guide. Place the valve spring and retainer in position and press the spring together with a valve spring ten- sioner. Fit the valve lock. Note: Observe care when fitting the valves and compressing the springs so that the valve stem seals are not damaged. Comparison between new and old rockers 1. Earlier rocker 4. The new rocker tip 2. Earlier rocker tip 5. Valve cap 3. 3. The new rocker 6. Valve Fit the valve caps when all valves are fitted. (Ap- plies to MD2040 and later versions of MD2O10, MD2020, MD2030 (Please refer to the note below i tem 5)). 4. 6. Oil in the rocker mechanism and fit the different parts.
Fit new plugs if these have been removed. 3 1