Piston -BGM PRO 177/187cc- Vespa PX125, PX150, Cosa125, Cosa150, GTR125, TS125, Sprint Veloce (VLB1T 0150001-) - Ø=63.0mm

The pistons of the BGM177 cylinder are manufactured by the renowned Italian piston manufacturer METEOR. The piston has a high silicon content. As a result, it has lower thermal expansion, is more wear-resistant and thermally very stable.

PISTON RINGS
Two 1mm thick piston rings, also made in Italy, minimize friction and thus increase performance and speed stability. They are also identical in construction to the piston rings used by Parmakit and Polini.

PISTON SIZE
The pistons are available in categories A-D. The categories mean an increase in piston diameter of 1/100mm per ascending letter.
The category letter can be read on the piston crown. The cylinder is also marked with a letter on its underside. Both should have the same category. If the cylinder already has a high mileage, a piston of the next higher category may also be used (e.g. B-piston in A-cylinder).

COATING
The pistons have a molybdenum disulphide running-in coating. This coating is removed relatively quickly during operation. It only serves to perfectly align the piston with the cylinder bore. Please note that the coating itself is approx. 2/100mm:

PISTON CLEARANCE
The piston running clearance should be between 5-6/100mm. This value refers to a piston without coating. The cylinder has a narrower running clearance (approx. 3-4/100mm) when delivered (with coated piston).

(US21218)