During our last trip to Italy we visited Meteor in Milan. Here is our video of our trusted piston manufacturer:
We are totally amazed at how professionally Meteor handles the subject of pistons. Anyone who thought that the piston was just a cylindrical component and that only the piston clearance, the position of the rings and pins, the window and the length had to match might be surprised to find that every piston has a shape that matches its cylinder. Meteor works in the thousandths of a millimeter range by adapting the piston to the shape of the cylinder bore at various positions on the piston skirt. This guarantees high performance with maximum service life. Unfortunately, no two cylinders in a batch are ever the same. For this reason, there are usually A and B pistons, for example, which are optimally adapted to the cylinder shape. Make sure you choose the same letter (A,B,C) when ordering a new replacement piston for your cylinder.
Also, a piston is never completely round when viewed from above, it is actually oval:
The piston factory
During the tour of the Meteor factory, we noticed how much modern high-end technology but also real manual work is required to produce a perfect piston. We have brought you pictures from Milan of the process of creating a piston, from development to the blank to finishing:
Presented: The piston in your scooter
The piston is a cylindrical engine component that moves up and down (in upright cylinders) or back and forth (in horizontal cylinders) in the cylinder of your scooter.
Task of the piston
The task of the piston is to convert physical pressure into movement in a reciprocating internal combustion engine and thereby drive the engine.
Components of the piston
The piston has the following functional areas:
a piston crown, which is in contact with the medium,
the piston skirt: the cylindrical component that fits into the cylinder bore with a small clearance -> "piston clearance",
the piston pin with its bearing, which connects the piston to the connecting rod.
Nowadays, engine pistons are mainly made from cast aluminum alloys, whereas in the past they were often made from cast iron. Pistons for petrol engines are characterized by a much thinner-walled design, which allows higher engine speeds due to the lower weight. In the area of the 1st piston ring groove, hard anodizing (hard anodizing) can sometimes be used to reduce wear and micro-welding. Some of the piston crown has flat pockets to accommodate the valves that protrude into the combustion chamber. The piston skirt serves to guide the piston in the cylinder barrel and is coated with a bonded coating on most pistons. To save weight, in many high-speed four-stroke engines today the piston skirt is offset inwards at the sides (at the piston pin openings) ("slipper" pistons).
The piston crown
The piston crown has one or more grooves for the piston rings, the uppermost of which are the compression rings and at least one lower of which serves as an oil scraper ring. Most pistons have two compression rings and one oil scraper ring. For racing engines, so-called 2-ring pistons with only one compression ring are also used.
The piston skirt
In two-stroke engines, the piston skirts can also be fitted with windows. In addition, most two-stroke pistons have locking pins in the piston ring grooves to prevent the piston ring joints from twisting and jamming in the control windows of the liner. On old engines up to the 1950s, a nose piston was common on 2-strokes to enable the gas change or scavenging process. More modern two-stroke engines, however, generally have a flat piston crown, as the scavenging or gas exchange takes place as a reverse scavenging with a change of direction in the cylinder.
The piston pin
The power transmission of the piston to the connecting rod takes place via the piston pin. This is mounted in a bore in the piston in the inwardly thickened part of the skirt. This bore often has grooves at the end for retaining rings ("circlips") to limit lateral displacement of the piston pin.
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