Main dimensions of piston, connecting rod, piston pin and piston rings
Piston
The piston is made of aluminum alloy and coated with a layer of tin to improve the running-in ability. The piston skirt is oval in cross-section and conical in height. Therefore, the piston diameter must be measured only in the plane perpendicular to the piston pin and at a distance of 52.4 mm from the piston bottom.
The hole for the piston pin is offset from the axis of symmetry by 2 mm to the right side of the engine. Therefore, for the correct installation of the piston in the cylinder, there is a "P" mark near the hole for the piston pin, which should face towards the front of the engine.
Since 1986, pistons of repair sizes for all engine models have been manufactured with an outer diameter increased by 0.4 and 0.8 mm. Before 1986, pistons of the following repair sizes were produced: for 2101 engines - with an increase of 0.2, 0.4 and 0.6 mm; for 21011 – with an increase of 0.4 and 0.7 mm.
Piston rings
The piston rings are made of cast iron. The outer surface of the upper compression ring is chromed and has a barrel shape. The lower compression ring is of the scraper type (with a groove on the outer surface), phosphated. The oil scraper ring has slots for the oil removed from the cylinder and an internal coil spring (expander).
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Piston pin
The piston pin is steel, tubular in cross-section, pressed into the upper head of the connecting rod and rotates freely in the piston bosses.
Connecting rod
The connecting rod is steel, forged, with a split lower head in which the connecting rod bearing liners are installed. The connecting rod is machined together with the cover, so when assembling, the numbers on the connecting rod and cover must be the same.