Scooterotica

I think with a bit more elbow grease with emery paper and then a touch up with a wire brush in a dremel you can do better than that.

The real question is will it run and will it cause detonation.? Ok that is two but...

I don't know the state of tune and whether Lambretta are prone to detonation. If not and the guy is strapped then show it to him and say that, to be like new, it needs to be machined but as it is it will run and will suffer no negative consequences.

I took a head of a two-stroke twin and it had similar damage caused by detonation, after 20,000kms. So I cleaned it up and it looks OK. Then discovering that the pistons are no longer available and that I have to fit two new Wiseco teflon coated ones, just out of curiosity I took the other head off and it is worse.

The point is had my "original" piston been available I would heave never looked at the front head/cylinder, out of sight out of mind, and would have been occasionally taking it for a ride.

If it is a fairly mild state of tune and or not thrashed to death then it will probably be fine. The damage is to the squish band and all that sanding and smoothing will reduce 'squish' effect so it will need to be checked again on assembly (1.2mm-1.5mm). If it is a tuned motor then I'd say replace it.

Cheers for the advice so far, it's a standard Megello 186, 28mm PHBH and Gori exhaust. He is still deciding if he wants it skimmed or a new head, hopefully he will decide on a new head

Looks like a recessed head so I wouldn't skim it the bit that matters the gasket face will be fine.. Loose any raised bits with a dremal and ignore any dents. Unless I've got it all wrong