Modern Vespa

So recently, I blew up two top ends due to what ultimately turned out to be a damaged crank.

In both cases, the cylinder survived, but the piston did not. This left me needing to replace pistons for both a BGM 177 and a cast iron Polini 177.

So let the search commence...

On the BGM, I got lucky. I had a "D" piston, which is the only replacement piston available. A, B, and C are all out-of-stock with no availability date listed at scooter-center.

For the Polini, I was hoping to swap over to a Grand Sport for some 1mm ring action, but came up completely empty from a multitude of web suppliers. Everybody and his dog had the oversize versions in stock, but even SIP had them on back order with an estimated availability date of Feb 2, 2019. That didn't fill me with confidence.

Now in the course of my search for a new piston, one of the things that I noticed is that while pretty much any oversized piston of any sort you might want could be had all over the place, stock replacement pistons are a much tougher proposition. I finally wound up getting a replacement stock Polini piston, but even that took an order from SIP. None of the Usual Suspects here in the States had one in stock, according to their Web sites.

So that, in turn, got me to thinking about what's going to happen to this hobby as the transport world as a whole shifts more and more to electric vehicles. At what point is our hobby simply going to become untenable?

If the replacement part supply chain is already getting this thin, what's going to happen once aggregate demand for parts starts to decline?

Maybe this is more me whining than worrying, but it still didn't give me warm fuzzies.

I figure we have about 30 -40 more years, then they'll all be in museums, garages or junk yards. Or converted to electric.
Meanwhile, most people with scoots ride hard once the weather gets good in the spring and trouble follows eventually. Parts run out.

If Vintage Motorbikes are anything to go by, when parts get scarce up will pop specialists who will make limited production runs... for a price.

same thing for Lambrettas, right? you can get the crap part from India for cheap, or the limited run expensive part made in Italy by the specialist company for 3x the price but the quality is good. if there is enough demand someone will make it but the price can be eye-popping.

I've been amazed at the the plethora of scooter parts being manufactured at the moment, and it seems to be on the increase even though the scooters are now out of production.
Could you have used a VMC 177 piston in your Polini? Until recently Scooter Center apparently used to sell a 177 BGM conversion piston to suit other 177's. But they said it didn't sell well and they're not doing a second production run.
Some useful info comes up in this group - https://www.facebook.com/groups/bgm177/

If I could've gottten a BGM piston for it, I would have. If I'd been thinking, I'd have measured the new D piston I got for the BGM top end in the Polini to see if it was an option.

As it was, I was hesitant to start dropping a hundred bucks a shot in the hopes that a piston would work. Ultimately, that may be one of the bigger challenges. I agree that the variety of performance parts available is definitely better than it was fifteen years ago when I first started messing with these things, but I also feel like there's a lot of single- or intermittent-runs of a lot of them at the same time.

In the longer run, I expect that electrification will be the trend, and for short/urban riding you can already build up a pretty hot motor and then build out a mount that matches the existing frames pretty easily. I'm still planning to take on my 4-speed manual electric project at some point. I need to hit Patrick up for the P125 cases with a crank in the fly side crankcase that he said he had. As I think I said over in V oodoo's thread, my fighting robot buddy pointed me to a 6KW brushless motor that has almost the same dimensions as a Vespa crank, which would make it basically a 20HP scooter with a full torque power band.

Good news is that I buttoned it up tonight and it's running again, without the irritating rattle that necessitated the teardown in the first place.

https://youtu.be/J3b4HTLe_YY

Sounds great. But I have no idea how you can just grab the plug lead like that!! I hate getting zapped so much!

+1 For the VMC piston. EUR50 and 1mm rings, would do the trick nicely.

I was thinking about 177 pistons the other day, as I have a new BGM 'C' on the shelf and a Pinasco Magny Cours cylinder that I would like to rework in order to get some nicasil porting experience. The piston is a good fit in terms of the bore tolerance and the compression height is the same. There are a few other considerations such as the position of the ring pins, the windows, the skirt, and the crown dome profile.

I also have a new VMC piston which was with the kit when it was delivered, but the supplier sent me a later revision piston soon after. I'm not too sure what the problem was with the original VMC piston and don't know if it can serve any purpose in another cylinder.

I'll take some photos of all three pistons side by side (BGM, VMC, Pinasco) and try to take accurate measurements. It might be that one one of these would work in a Polini 177 cylinder with minor mods.

All I need now is a couple of small block engines on which to use this stuff, as I seem to have accumulated a lot of 177 components, yet spent 2019 playing with my 200 based scoots.

Of course it would depend on compression height as well as the things mentioned by SWA... but certainly worth a look to see what options there are available.