Modern Vespa

I have read some threads about changing the rings on my two-stroke scooter, but I don't see anything about cylinder bore prep. On every automotive and tractor engine I've rebuilt, it is necessary to remove the ridge at the top of the bore where the ring travel stops (bore wear is only below that point), bore to the next oversize unless wear is minimal, and finally hone the bore so the walls have a new cross-hatch pattern.

Is the scooter cylinder bore made of a super-hard material that doesn't require this attention (assuming that the piston hasn't seized)? If the piston and bore look good, can I really just pop in a new set of rings and gaskets?

Honing the cylinder bore is more applicable for cast iron cylinders.

If the cylinder is made of aluminum, it will have a Nikasil lining which is more wear-resistant than an iron bore lining. Honing these requires a 400-grit or better diamond-compound hone and isn't quite practical for a home mechanic.

thanks, that makes sense. I didn't realize the bores were Nikasil instead of iron-sleeved... that's a great material except for one little thing:

I've been driving and working on my BMWs since 1988 and Nikasil was a four-letter word for a while: https://www.bimmerforums.com/forum/showthread.php?1957814-M60-Nikasil-recall BMW learned an expensive lesson and replaced a lot of engines under warranty with Alusil blocks. Guess the refineries fixed the sulfur in the gasoline eventually... not sure about European fuel and this scooter (made in '00).

Anyway I ordered a complete kit (cyl, piston, rings, gaskets) and on teardown if they look good I'll just change the rings and gaskets

Good strategy.

Fair play on Nikasil concerns. At least sulfur is no longer as big of a factor.

As for crappy cylinder coating, I'd still put hardchrome at the bottom of that ladder. I have an Aermacchi 2T with 420 miles on the bore. Aermacchi switched from cast iron bores to hardchrome aluminum in '74. While this bore is quite serviceable, I intend to ship it off to have the plating removed and the bore recoated with one of the silicone-based coatings so it may last a bit longer than it's peers.