Modern Vespa

I've been slowly working on a stock '78 P125x since last fall (not my first project bike or 2-stroke, but my first Vespa). Sorting out the front end and controls. Just about to pull the engine and do the pivot bushings, and see what else might be lurking that needs attention.

I'm fine keeping it stock but curious if converting to a (stock) 150 is as simple as changing out the top end? Would it likely need the next size up carb as well?

Thanks for input in advance.

When i put a 177kit on my p125x, i got a bigger carb. It was only problems. Its been pretty smooth sailing after putting the original 20/20 back on, and re-jetting. From what I understand, the 20/20 can handle quite a bit.

Converting from a 125 to 150. If using stock or stock like parts. The 20/20 is absolutely fine.

The 150cc from piaggio uses the 20/20 anyway!

Just change your jetting stack to match the piaggio 150 stack and you should have many many miles of trouble free motoring

Thanks for the replies.

The exhaust spigot would be the same size as the 125?

Same setup for gaskets, no head, but base?

The same.

Thanks. Timing the same as well?

Indeed it is

It's the 200 that had different timing.

Very informative. Thank you.

A question about the Vespa oil pump.

As a kid, my first bike was a Yamaha with auto lube. As a teenager, then young adult, I had a couple of bikes that relied on premixing. Although a bit of extra work, I preferred it knowing the engine would always have adequate lubrication and not worry about a pump or feed tube failing.

Anyone out there switch to premixing a Vespa with an oil pump? Should the pump and shaft be removed if doing so? Or would leaving it be ok to do? Or is the pump very reliable?

Thanks in advance.

With a stockish motor the oil pump is usually very reliable and is BETTER for the motor because the connection to the throttle gives feedback for more or less oil % depending on demand. Do a search to know how to test it, or somebody will soon post a link.

Theres hardly any noticeable difference going to a 3 port 150 cylinder, maybe 1mph. To be honest, if you want the cheapest bang for buck, stick a Sip Road 2.0 exhaust on it, a drilled air filter (or Piaggio unrestricted air filter, which do exist) and up your main jet by 5 points. Its likely on a 96 main jet so take to 101. That way you keep the scooter as its originally intended 125 (important in the UK as thats the learner limit). Its the simplest thing you can do and will give you better performance than going to a 150 pot and save all the changing registration details, insurance etc. Finding an original Piaggio 150 PX cylinder is pretty difficult; all the stuff online will likely be Indian garbage, or LML. Some of the later LML 150 cylinders need faffing about on the jets because although they have 3 main ports, they also have extra boost ports. You have then got to run it all in etc.

Thanks. That sounds like a good option worth considering.

Good to know. Thanks.

https://www.rondaleyscooters.co.uk/products/air-filter

If you see picture 3 of 4 you can see the heart shaped cutout with the drilled out holes that sit over pilot and main jet . You did message me asking about this but I'm not sure if my message sent . Cheers buddy

Another question.

I've removed the engine to thoroughly clean it and replace the rubber engine buffers in the swing arm.

It's got the original full length tube, two rubber buffers, and peened-on end washers. All removed just fine. There was one large inner washer on the left that the rubber seated onto. Not one on the right, which according to parts diagrams there isn't one.

I have newer style two-piece buffer replacements with tubes that meet in the middle. I do plan on taking some additional frame and old assembly measurements but is the large left inner washer needed with the new two-piece style? And I assume the old peened end washers are not needed, correct?

Thanks in advance.

Isn't SIP producing performance 150 cylinders? A little more pep than stock but not as much as going to a 177?

[With the new bushings you have all you need.

Some aftermarket need no additional washers and the old ones should all be removed.
BGM provide washers for there own and you just use theirs NOT the original ones

Zooming in on your new ones, as long as you removed all washers, install as is

Thanks for the input. Haven't found much info about the installation.

I'm anxious to get the engine back in, new hoses and cables hooked up, put in a new airbox base gasket, and clean and rebuild the carb.

I have the SIP Road 2.0, filter, and jets on the way to play with as I get nearer to getting it back on the road!