Scooterotica

I've been looking on the MBD / Lambretta spares site and I'm not locating an explanation to the "A thru D" scaling system they use for the Race-Tour pistons.

What's the difference between the A to D grades? I think I remember reading about it in scootering a few years back, but I'm not feeling like looking thru my old issues.

Little help?

thnx

The grading is the same for any piston suited to a nicasil lined cylinder which will also be graded to match. It's a size thing