Modern Vespa

I've got a friend who wants me to build a GS150 VS3 with a PX200 engine as is going to haul a sidecar. Definitely something that I don't condone but I don't think it will be a permanent thing as he does have the original engine with it. My query is can someone who's done this before tell me what's required and if there is any frame modifications needed to make it happen. From my understanding is front engine mount conversion bracket and rear shock adapter, rear wheel might be offset to original front rim? Worse bit is potentially hacking a section of frame out for the carb box but not 100% on that one, also clearance for the cylinder barrel/head? Thank you in advance!!

The best thing you can do for your buddy is to talk him out of it and a better machine for a sidecar and maybe talk him out of that too.

I get your vibes, haha!!

We have Vespa World Days coming up near us next year in March and he needs a sidecar rig for him and his wife, I don't think it'll get too much use after that. Unfortunately the Sprint that I was originally going to use for it was beyond repair after sandblasting reviled some structural damage. The GS is the "Hail Mary" pass.

THIS IS THE WAY

I was going down that route once. Yes, a big chunk out of the frame is needed for the carb. The SI style carb and airbox is a tough one to make work. I've seen people cut up the box and run it without the top. A round slide carb and custom intake would be easier to fit.
The adapter to the frame is easy enough. Big problem is the 200 size cylinder. The frame above the right engine mount bolt needs to be cut as well. The rear shock isn't hard to adapt to the upper mount but puts a nasty side load to it without offsetting the base to the left. This is of course with the engine centered in the frame. Other conversions have the engine offset to the right as much as possible but at the cost of rubbing the cowl and presumably piss poor handling. Makes the rear shock alignment worse as you can imagine. A 150 size engine would be an easier swap for sure. Overall, it's a bad idea in my opinion. It really needs a good butcher job to shoehorn an engine in there.

I found all the parts to rebuild my original engine and it runs great now. Will be putting the SIP cylinder kit on when that comes out. If there's something I missed, let me know. I'm sure I've left a couple other things out.

T Thanks Rob for the answer to my question. As I said, it's not something that I'm going to recommend him do, as it'll be a terrible solution to a problem that can be solved other ways. I been keeping an eye on your build and am very much looking forward to seeing it progress. Thanks again Rob.

Nothing takes the soul out of a widebody like putting a large frame engine in it.

I've been around long enough to know that it's not a good idea to go around putting 200 engines in GS frames, my post was confirming the actions need to do such a conversion so I can lay it all out as evidence to ensure my friend that it was not as simple as a straight swap like a 200 in VBB, etc.

You could shoehorn a 150 motor into a widebody frame w/ no irreversible mods, but the bigger 200 top end wont fit without significant frame modifications according to those who know.

But putting either large frame engine in an originalish GS150 should be a felony . Tell your buddy to sell it for big money and buy my shabby VB1 cheap, then do whatever else you want to it guilt free. Ran when parked.

vee bee one- got gas gauge, almost got seat!

The sidecar I tótally get; have my 5th now. 3 of the previous were MZ 250s.
A sidecar is something else. Although cálled a motorcycle/scoot with sidecar it is nothing like a motorcycle/scoot. Steers differently, behaves totally differently.
I lóve it. NÉXT to having a motorcycle/scoot.

As to the original idea I get that too; a bit more oompf seems a good idea lugging extra load around but as the concept of a sidecar scooter is not nimble or spritely like the solo scoot; best keep the combination sweet behaving. If he needs extra pulling power, reduce the gearing. Ah and make sure he has a very good clutch.

Hope the friend gets his ducks in a row and can enjoy riding with his wife.

The value that would be wiped off the GS150 would fund a half decent P series plus whatever mods were required to mount and haul the sidecar.

Could you fit a Quattrini 172 to the GS 150?

This says it fits but case might need work.

https://www.sip-scootershop.com/en/product/racing-cylinder-quattrini-m1xl-11-172-cc-for-vespa-125-gtr-2-ts-150-sprint-2-v-super-2-px125-150-pe-lusso-cosa_15046100

I've installed a stock P200 engine in my VB1 wideframe. My frame was toast, so i didn't feel bad whatsoever to lop and chop the sheetmetal. It was a very fun, very very challenging project for me (and i've done quite a few custom builds). Both Bajarob and Voodoo are spot on with the reasons why a P2 engine won't fit….correctly. Sure, we've all have heard about people quickly and easily swap in a P2 lump, but after doing one myself, i'm now really curious how they did it so that the centerline of the front and rear wheels line up. My guess is that they're not.

I do plan to build up a second knackered up VB1 wideframe with a P engine, but i'm not going to attempt a 200 again. This time it will be a very low mile 2005 PX150 engine that's getting transplanted (and kitted).

I'm not a purist, but even i wouldn't go modifying up a GS150 frame. A few years back i made a wish list of performance wideframe parts (Pinasco cases, close ratio 4 speed, mild cylinder kit, carb, fancy clutch, reed valve, ect, ect, ect). I think it added up to around $4500~$5000 USD (no labor included). I'd take whatever money that's going into rebuilding a P200 and invest it into a wideframe engine.


A link to my VB1 200 build. And FYI, since the thread is more than 2 pages long, you know it means that nothing was straightforward or easy.
1958 VB1 200 Wideframe scuttle bucket