Modern Vespa

Hi as I have taken the cylinder head off I thought sod it and took the barrel off to replace gasket..
Once off I have noticed a nasty bit inside barrel..
So questions are
1...can you rebore the barrel
2...how much can you take off
3..can I go over 200cc rather than buying malossi kit

I've seen a few OEM vespa cylinders that look like that. If you want to go with a 200cc kit, you can use the stock Piaggio 200cc cylinder and piston, without changing the head. You might run into issues with the carburetor, but should be able to resolve those with a smaller main jet than the one in the 125 carburetor.

Thanks for reply motovista..the 200cc I thought was only 180cc due to the same crank as 125cc..
Piston wise I thought 125 was 50mm something 200 60mm something and the malossi kit 70mm something..
I was thinking it might be cheaper to rebore and new bigger Piston and rings than to purchase the malossi kit..

There was Gilera Runner and Hexagon with the 180 LC version of the motor, but the GT 200 motor is 198ccs. 72mm bore. The Malossi 209 kit is discontinued, and the 218 kit is 75.5mm bore.
If it was my bike, I would go with the 200cc Piaggio cylinder. The Malossi kits don't make as much sense without the Malossi head, and they have been out of stock for a very long time.

Thanks again motovista..problem solved then with 200cc piston size..
I have looked for a 200cc barrel and piston and can't find one anywhere..I can get a gilera 200cc barrel and piston 2nd hand from Italy but piston appears different..
I have found on ebay a guy selling the full malossi kit..barrel..piston..head..cam..for £680 from Italy..but can't translate Italian lol..

You thought of a engine transplant 250cc leader £550 ebay several on there or even just use the head.

Hi bugsy the 250 is fuel injection and means you have to change the loom and petrol tank..better to have crashed bike and change everything over..

Yeah you're right talking to another local GTS owner today about it, looks like you are stuck between a rock and a hard place, you made a decision on what you're going to tackle it mate. y

Hi bugsy yeah right old mess it is..not sure I can be bothered with it now as purchased another bike..I've put it up for sale and if it doesn't sell..Will give me time to buy items needed to finish..I never had problems with getting parts for my t5 or lambretta and that was before Internet lol..

Looking at the pictures of the cylinder it looks quite bad to me. I would not machine it but replace it.

You have the engine open.
Did you consider to simply buy an original Piaggio cylinder and piston?
I was told by a colleague these original Piaggio parts are not expensive.

Hi yes the barrel is buggerd so will go in the bin ..a new 125cc barrel and piston new from sip is £170 plus postage and new gaskets..I was hoping to make it go a bit faster especially on dual carriage way..hence wanting 200cc..

I see.

My thoughts:

Upgrading from a 125cc to a 200cc with only changing cylinder and piston will not bring you much with respect to speed.

It will probably bring you faster acceleration but not higher speed because you leave the transmission unchanged and that one is tuned for a 125cc engine.
The 200cc will not rev higher than the 125cc and higher revving is the only way to gain speed in that case.

(not mentioning problems with the law when switching to a significantly larger engine in case something would go wrong with someone else being involved)

So, again my thoughts:
I would bring the engine back to original. And make sure it is really running perfectly.

Then if you think the 125cc is not meeting your expectancies sell it and go for a GTS 300.

Hi the 125 and 200 are the same engine except bore size..so adding a 200 barrel would obviously improve the performance compared to 125..the rest of the performance engine parts will come once I have resolved the barrel problems 1st..I have found a company that will do performance work on the cylinder head ..
I'm not worried about the law and they have more things to worry about than 75cc lol..
I certainly wouldn't buy a 300 gts not reliable