Technical information

C
24 08.06
CHAPTER
PAGE ISSUE
TWO-STROKE ENGINE AM6
ENGLISH
SECTION 2
C - ENGINE
Minarelli Engine
F.33
F.32
RINGS DISTANCE
New 0.15  0.30 mm
Used up to 1.0 mm
6) ENSURE that the clutch assembly is in working order.
To do so, ensure that the iron discs are in good condition, that the notches on the cork discs are not too
deformed and that their coating is not burnt. Check that the grooves on the clutch boss are not too deeply
marked; perform the same check on the slots of the clutch housing. Also check that the clutch springs are
not shorter than the permissible threshold of 29.5 mm (F.31); if they are shorter replace them.
7) CAREFULLY clean the carbon crust from the piston top by means of a common scraper, taking care not to
damage the piston itself. Check the piston skirt for streaks or seizing. Check that it is firmly mated to the
lubricated piston pin, the surface of which must be in perfect condition. Make sure that the piston pin can be
fitted by manual pressure and that it does not yield under its own weight.
8) CHECK the piston rings for faults of any type and make sure that the clearance between the two ends is within
the values shown in the chart.
PISTON RING DISTANCE
The checks must be carried out using a feeler gauge. The piston ring must be placed in the cylinder in a
horizontal position (F.32).
9) CHECK that the cylinder water jacket does not have seizing notches or wear and that there is no scoring of
any kind. By means of a bore gauge, check the cylinder bore in two directions at 90° the one from the other
(one parallel and the other perpendicular to the axis of the piston pin) (F.33). The maximum permissible
ovalisation is 0.03 mm, exceeding which the cylinder must be replaced.