Modern Vespa

Hi all,

I am looking at a Vespa P200, which is in decent shape body wise and seems like a good deal.

One thing that has me concerned - supposedly the previous owners ran the scooter very lean, which resulted in a blown piston. I guess it blew a hole in the top of the piston head. To fix this, the guy rebore and got a new piston, so the engine is now technically a 205cc. What do you guys think of this? Is this a big deal? Will this affect performance in bad/good way? Perhaps this won't matter if I drop in a kit?

If the job was done right, nothing to worry about.

Yep a rather regular job having an old cast iron cylinder a slightly larger bore and a oversized piston

remember that the displacement of the engine ( 205cc ) is just a simple multiplication of the bore (width of the cylinder opening) times the stroke ( distance of travel ).

The stroke will stay the same as long as you use the same crankshaft / conrod ( you'll hear sometimes people putting on a "long stroke crank" on a tuned engine, to gain more displacement ).


Oversize pistons / bores on scooters is no big thang, as was previously mentioned.

I think the 20th oversize on an SS180 is a 200cc ...so it's a common conversion for people to bore it straight out to that, and drop in the big piston for the added displacement.

Lambrettas, too ... many people will bore out an LI125 or LI150 jug to 175cc specs, and run an oversize piston to basically make it an LI175. ( the TV175 has a longer stroke con rod, so if you continue to use the LI-style crank, you have a shorter stroke but a wider bore to come to the same displacement.

Simple math. Make sense?

In any case, proper gapping of the new rings and a well-performed break in period make all the difference.