Modern Vespa

Bought a bike with a p200 engine. Started up fine after I replaced the fuel line and decoked the top end. Needed some fresh cables, so I replaced them and tried to fire it up again, ride it around: no dice.

Compression check showed 65PSI. Oddly enough, this has actually happened a few times over: a bike starts and runs fine when you go to check it out, but you take it off the truck and it wont fire up because the compression was so low in the first place. it boggles my mind.

Anyway, I ordered new rings and went to put them in: bam. Scoring on the cylinder.

I've attached pics of the 'top' of the cylinder, the part you can see with the piston at Bottom Dead Center (BDC): no scoring there. You pull it, and where the piston sits at BDC is where all the scoring is. Nothing that can catch a nail but it has definite grooves.

Looks totally mucked, mate.
'
What's a cheaper solution: overbore + new oversized piston + oversized rings?
or fresh piston/ring/cylinder combo?


Piston Scoring

Bottom Cylinder

Top Of Cylinder

Cheaper or best option?...lots of the current aftermarket stock sized cast iron cylinders and pistons kits aren’t near the quality of the original cylinder. It will cost more, but my favorite is an overbore on the stock cylinder, along with the appropriate sized “GS” brand piston.

I’ve had some machine shops charge me $65 for a overbore, and other charge me $35.

Southern California prices $40 for the bore and $80 for the piston. New stock top end

$300 for a new stock cylinder/piston

Looking at it I would say a hone and a new piston. I've had worse pistons.

Use a Flex Hone but you need to buy the correct size.

Replace us pretty cheap...

http://www.scootermercato.com/Scooter-Parts/Cylinder-Assembly/414708