VERTEX | Ref: 2868

Vertex Piston Yamaha YZ 85 02-15

  • _Vertex Piston Yamaha YZ 85 02-15 | 2868 | Greenland MX_
  • _Vertex Piston Yamaha YZ 85 02-15 | 2868 | Greenland MX_

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VERTEX | Ref: 2868

Vertex Piston Yamaha YZ 85 02-15

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Technical details
Size guide
; italian made ;pistons ;for high-performance motorcycle racing applications Vertex are the unique piston profiles and compression ratios that are offered in a, b, c and d sizes This variation in sizing, a mere 0 004", allows the piston to be perfectly sized to the cylinder for maximizing power and performance while reducing blow-by and oil consumption You can specify in remarks, piston detail ;


The pistons of any internal combustion engine, two or four-stroke, are conical and oval, to control its expansion in its operation. To get to know your maximum measurement you have to measure at 10-12 mm. of the skirt, in the opposite part to the bolt.

When we see a mark on the head of the piston, for example, 80 mm. or we have a cylinder of 80 mm. this measure is corresponds to the cylinder, when meassuing the piston we will see that actually measurement is 79.95 mm., the tolerance between piston and cylinder would be 5 cents (0.05 mm.).

In the aluminum cylinders with hard chrome interior treatment, already in disuse, or NIKASIL the measure of 80 mm. It is usually fixed to 80 mm.

The pistons work with tolerances between 4 to 6 hundredths (0.04-0.06) for two-stroke engines and 3 to 4 hundredths for four-stroke engines (0.03-0.04). To fix a deformed cylinder, the interior of the cylinder shall be polished first and the measurement is adjusted with pistons that are over-measured for this purpose, marked with letters A-B-C-D (selection); the lowest measure being A, increasing 1 hundredth per letter; that is, selection B 0.01 mm. greater than A, C 0.02 mm. greater than A, etc.


New Cylinder Ø 80.00 mm. mounts a piston of Ø 79,97 A Factory Tolerance 0.03 mm.

Polished Cylinder Ø 80,01 mm. mounts a piston Ø 79,98 B Factory Tolerance 0,03 mm.

Polished Cylinder Ø 80,02 mm. mounts a piston Ø 79,99 C Factory Tolerance 0,03 mm.

Polished Cylinder Ø 80,03 mm. mounts a piston Ø 80,00 D Factory Tolerance 0,03 mm.

The important thing is to maintain the tolerance, which the manufacturer recommends, between cylinder and piston.

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