User Guide

Checking the oil pumps for wear

– Place inner and outer rotors into the engine casing such that the marks

are adjacent to one another.

– Now, carry out the following wear measurements with a feeler

gauge

outer rotor - oil pump housing: max. 0.20 mm (0.0078 in)

outer rotor - inner rotor: max. 0.20 mm (0.0078 in)

5-9C

Checking the piston

– Replace the piston in the case of excessive oil consumption or grooves

in the piston skirt.

– If reinstalling the old piston perform the following steps:

1. Piston bearing surface - check for damage.

2. Piston ring grooves - the piston rings must move easily in the groove.

Old piston rings or sandpaper (400 grit) may be used to clean the

piston ring grooves.

3. Piston rings - check for damage and end gap (see below).

Mount the oil scraper ring with the labeling "TOP" facing upwards.

Mount the rectangular ring with the labeling "O" facing upwards.

4. Piston pin: If the piston pin is heavily discolored or has score marks it

must be replaced. Also insert the piston pin into conrod and check its

bearing for play.

NOTE: When in place, the piston pin may not have any play. It must be

possible to shift it with slight counterpressure.

Piston ring end gap

– Insert piston ring into the cylinder and adjust. Piston ring must be

approx. 10 mm (0.4 in) from top of cylinder.

– The end gap can now be checked which a feeler gauge

Compression rings: max. 0.80 mm (0.0315 in)

Oil scraper ring: max. 1.00 mm (0.0393 in)

If the end gap is larger, check piston and cylinder for wear. If piston and

cylinder wear are within the permitted tolerance limits, replace the piston

ring.