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MP3 400 i.e.
Check the size of the sealing ring opening:
Compression ring: 0.15 ÷ 0.35 mm. Max. value 0.5 mm
Oil scraper ring: 0.25 ÷ 0.50 mm. Max. value 0.65 mm
Oil scraper ring: 0.25 ÷ 0.50 mm. Max. value 0.65 mm
Rings/housing coupling clearances:
Carefully clean the sealing ring housings.
Place a thickness gauge between the ring and the
housing as shown in the drawing and check the
coupling clearances.
Top ring Standard coupling clearance:
0.01÷0.06 mm
Maximum clearances allowed after use: 0.10
mm
Intermediate ring Standard coupling clear-
ance:0.02÷0.07 mm
Maximum clearances allowed after use: 0.10
mm
Oil scraper ring Standard coupling clearance:
0.01÷0.06 mm
Maximum clearances allowed after use: 0.10
mm
Replace the piston if clearances exceed the max-
imum limits specified in the table.
Crankcase - crankshaft - connecting rod
Crankcase / countershaft coupling
Besides considering it should match the crankshaft, the crankcase is chosen according to the centre
to centre distance between the seat of the crankshaft and that of the contra-rotating shaft.
Both the centre to centre distance and the pair of gears driving the contra-rotating shaft are divided into
two types (A and B) to be matched (A with A and B with B).
This selection is useful to keep the difference between the working distance of the gears and their
distance without clearance at a given value in order to avoid abnormal noise.
Specification
Centre to centre distance of the gears without
clearance
Centre to centre distance on the crankcase
TYPE A
Desc./Quantity
76.937 ÷ 76.867
77.022 ÷ 76.992
Characteristics
CHAR - 11
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Troubleshooting
