GRAND-SPORT has marketed their own racing piston since 2004, and no piston product has influenced the Vespa scene like theirs. GRAND-SPORT aka GS-Pistons enjoys years long recognition and has driven home countless successes in all VESPA race series. When it comes to cast iron cylinders and power, most only want GRAND-SPORT piston products.
High quality metal alloys with at least 18% silicon, contemporary design and lower compression height rates guarantee durability and no freeze assurance. It goes without saying that a piston shirt with cutout and w/o cutout for do-it-your-self is status quo, like additional surface coating on a molybdenum disulfide basis. The special lubrication gives the pistons optimal running operation, reduces friction and gets fantastic results when breaking in both piston and cylinder.
Furthermore, GRAND-SPORT pistons are equipped with 2 1mm high quality pistons rings made of steel.
A further plus: lighter biconical gudgeon pins.
Conclusion: if high quality materials, well thought out technical details and dependability are what you're looking for, this is it. GRAND-SPORT pistons are a byword for powerful and durable cast iron cylinders.
Aluminum/ ø 57.00/ 57.72/ 58.00mm/ coated pistons / 1mm piston rings
Coated aluminum pistons, minimum 18% silicon, 30.5mm compression height, appropriate pin distance for POLINI/MALOSSI/DR. ZIRRI, 1mm piston ring of ductile cast iron, biconic gudgeon pins.
This cylinder requires modification to be fully compatible with the compression height of the new piston. The exception from this rule is provided by the piston included in the MALOSSI 136cc cylinder kit with its ideal compression height of 30.5mm. The compression height of the POLINI and D.R. Pistons is 36.0mm, the ZIRRI piston has a compression height of 32.5mm.
Before installation, always control piston play and piston ring stop play and adjust if necessary!
SIP-TIP: Main jet adjustment and new spark plugs are a must.