Remove the fuel supply hose from the fuel pump to the carburetor and the crankcase ventilation hose running from the cylinder head cover to the carburetor. Remove the hose connecting the carburetor to the vacuum regulator of the spark timing sensor.
Disconnect the throttle drive rod from the carburetor. Remove the carburetor with the gasket and the intake pipe with the gasket and the bracket of the intermediate lever of the carburetor drive.
Remove sensor 1 (figure 30) moment of spark formation with sealing ring 2, and then fuel pump 7 together with heat-insulating spacer 5, pusher 6 and gaskets. Remove housing 3 of auxiliary units with sealing ring 4. If complete disassembly of the engine is not required, then the cylinder head can be removed as a whole with the carburetor and auxiliary units.
Remove the tension bar and the alternator drive belt, and then the alternator by unscrewing the bolt that secures it to the front suspension support bracket of the power unit. Remove the front suspension support bracket of the power unit by unscrewing the mounting bolts. Lock the flywheel with the 67.7820.9534 lock (see figure 35), unscrew the generator drive pulley mounting bolt and remove the pulley from the crankshaft.
Remove the front cover 1 (figure 31) toothed belt with rubber seal 2. Unscrew the tension mechanism fastening nut. Loosen and remove toothed belt 3. Remove tension roller 6 with axle 7 and spacer ring 5. Holding pulley 4 of the camshaft from turning with device 67.7811. 9513 by the pulley holes, unscrew the fastening bolt and remove the pulley. Remove toothed pulley 8 and key from the engine crankshaft.
Loosen the pump mounting bolts 2 (figure 32) coolant. Loosen the bolt and nut securing the rear cover 1 of the toothed belt and remove it together with the coolant pump and gasket 3.
Disconnect the hoses from the suction pipe 2 (see figure 8) and outlet pipe 11 (see figure 9) and remove the thermostat with hoses. Remove the coolant pump inlet pipe and outlet pipe with gasket. Key 67. 7812.9514 (tubular end 21 mm) the coolant temperature gauge sensor and spark plugs are unscrewed from the cylinder head.
With the device A 60312 (figure 33) remove the oil filter with the gasket. Disconnect the crankcase exhaust ventilation hose from the pipes on the cylinder head cover and on the rear crankshaft oil seal holder. Remove the oil level indicator.
Unscrew the oil pressure warning light sensor from the oil filter flange, and then remove the oil filter flange with the gasket.
Remove the cylinder head cover with the gasket and rubber bushings. Unscrew the cylinder head mounting bolts and remove it together with the camshaft. If necessary, disassemble the cylinder head (see section. "Cylinder head").
Turn the engine over with the crankcase facing up and remove the oil pan 5 (figure 34) with gasket 4. Remove oil receiver 3 and oil pump 1 with gasket 2. Unscrew the nuts of the connecting rod bolts, remove the connecting rod caps and carefully remove the pistons with connecting rods through the cylinders.
Block flywheel 2 (figure 35) retainer 5 (67.7820.9534), using key 1, unscrew bolts 3 securing the flywheel, remove washer 4 of the bolts and the flywheel from the crankshaft. Remove the rear crankshaft oil seal holder.
Holding the middle part of the balance shaft from turning with a "27" wrench, unscrew the bolts securing the balance shaft gears and remove the gears. Remove the main bearing caps together with the lower liners. Remove the crankshaft from the bearing seats, and then the upper liners and thrust half rings from the middle support.
The balance shafts are removed only if it is necessary to replace the shaft or its bearings. Removing the shafts is described in the section "Cylinder Block" (see section. "Disassembly and assembly of engine components").