Modern Vespa

Ciao, Vespisti!

Over the past week, I've noticed my scooter's power has been a bit lower than usual. I usually reach 43–45 mph, but lately, I'm maxing out around 38–40. The last few days, I've also noticed a slight "chugging" feeling, like there might be too much air in the system.

Today, I got about five blocks from home before the scooter died. Thankfully, thanks to all the great advice from this group, I now know my way around under the pet carrier, so I took a look.

It turns out my airbox is just sort of hanging loosely inside the body—it seems like it's supposed to be attached to something that's no longer there. Because of this, the intake hose had disconnected. I reattached it, but the scooter still won't start.

I checked over the engine, and everything else seems fine. The engine turns over, but it won't catch, and the kickstart didn't help either.

Any ideas on what to try next? 😅

It sounds to me like.. no spark or no fuel.
Combustion just needs, fuel, air and a spark.. in right ratios, of course. 🤪
I think it has one of those pressure-driven fuel taps… with 2 lines.

One hose pulls from carb pressure to pump fuel through the other.
If the diaphragm inside has failed, it wont blow fuel.
Disconnect the fuel line from the tap and crank it over. It should squirt gas. If it doesnt…the tap is suspect or its not getting the pressure from the carb/piston cycle.
Replace that line and remove the other one from the tap, put your thumb over the end and crank it over. You should feel air pressure.

https://modernvespa.com/forum/topic187746

If not..possibly shot rings? 2 stroke, right?

Gradual loss of power then no run? Hmmmm.
Could be as simple as…or more.
Check the fuel tap/delivery first.

Awesome — thank you for your help and for the linked thread with diagram! I will give that a try. 🤞🫶

I am having similar problems and my local dealer told me that it is definitely the reed valve, partly because I've already replaced CDI, Carb, lines, plug and air filter. Reed valve prevents blowback and sits just under the intake manifold. I'm replacing the manifold as well just to ensure good vac. Haven't gotten parts yet, but they swear that's the problem. Maybe check that?

I'm pretty sure it's not the reed valve or intake, as I replaced the intake manifold and cleaned the carb a few months ago.

At this point, I feel fairly confident that the issue is vacuum-related, as I am able to pull fuel while sucking on the vacuum tube. Connections, seals, and gaskets all look good, from petcock joints to carb joints to air box to intake.

I sprayed carb cleaner over the joints as the engine turned over and didn't notice anything useful. Holding down the start and letting it turn over for an extended period isn't helping, but occasionally the engine almost catches and the headlight comes on briefly.

Repeatedly killing the battery while trying to start up is really cramping my style, though, haha. I keep having to charge and try again.

I'm not sure what to try next and would love any suggestions or advice! Thanks so much! 🫶☺️

Rent-borrowing a compression gauge from a friend or auto parts store is probably in order.

Well, folks are still trying to help me with another of mine…so I'll keep thinking about yours.
Here's a link to a manual.. just in case.
https://www.manualslib.com/manual/1356876/Vespa-Et2-50.html

Not being able to see or hear it… it turns over..makes compression, has fuel to the carb, at least…
Does the spark plug get wet..indicating its getting fuel, just not igniting. After cranking it, pull it and look.
I dont know what the airbox looks like..but theres not a loose snorkle or something?
I have a 49cc minarelli also and its not difficult for the airbox to dislodge..and too much extra air will make it too lean. I think they're already lean, for EPA.
Also, can you put a thumb over the spark plug hole and turn it over. It should at least pop your thumb off, as a seat of the pants compression test.

Seconded on the compression check.

Any luck resolving this, OP? Still waiting for my reed valve and intake manifold from Italy. LOL

There was a general strike in Italy on Friday. Maybe that caused a delay.

As far as the OP's issue, if you were riding it for a long time with the air box off, and it seemed a lot faster than usual all at once, you likely burned up the top end.
What color is the spark plug?

Oh, man.. sorry to hear that! It's frustrating to have to wait for parts when you're raring to start fixing. 😐

My problem is ongoing, but that seems to be par for the course with this bike. I'm the second owner and it seems to me that it was sat in a garage for most of its previous life, so every time I attempt a repair, I run into unexpected issues. It would be comical at this point, if it weren't so annoying and costly! 😅

I went to pull the spark plug and discovered that the socket in the toolkit was too small — because of course it would be. 🤦‍♀️🤬

Anyhoozle, I got the right-sized socket, pulled the spark plug yesterday, and based on appearance, it does seem that I need a new one. Plus, it was NGK BR7ES, which isn't ideal.

Spark plugs are arriving today or tomorrow, so 🤞🤞🤞

I'm not sure how long the air box was off, but I had been noticing a slight reduction in power and speed for a week or two. Since we're on the topic, do you know what the air box is supposed to attach to on the frame? It seems like it shouldn't be able to flop about like mine does, it's just rested on whatever's underneath and likely contributed to it becoming detached.

The spark plug electrodes are definitely corroded and have a little carbon buildup. The plug threading has carbonization and no sign of oil residue. I also discovered that one of the shops I used put an NGK BR7ES in there.

I can't wait to put a new plug in and (hopefully) fire her up! 😁

It bolts to the engine above the variator cover. There will be a couple of places to stick the bolts under the air filter, unless they broke off. Is the rear fender, not the mudguard, but the curved piece of plastic that goes over the rear wheel, also flopping around? One bolt usually holds them both onto the engine.
Now this is from memory, and I haven't seen an ET2 up close in a while, but that's fairly standard Piaggio modus operandi.

Yeah, always tough to tell true labor issues from it just being ... you know ...Italy. The guys at my local Vespa show are actually Italians, so they are completely unfazed by delays. IYKYK

Put a new spark plug in and still not catching and starting. I have tested fuel, compression, battery, and spark — all are good.

What now? 😭😆

Its a CDI i think…
Makes spark..compression.. getting fuel.. cranks over…. But fuel doesn't ignite.
Too much air or too much gasoline in the mixture.
You said the airbox isnt right, correct?
My Minarelli 2T, same as that one i believe, has a Gurtner 12y carb with an elec-choke.
Does yours?
Is it functioning?

Finally got my parts from Italy. It wasn't the reed valve. I can get it started and even rev it out pretty high. But, when it comes back down to idle, it stalls out. Any ideas? Could it be as simple as idle speed? I've replaced air filter, carb, fuel line, reed valve and intake manifold. Air leak? Compression?

How is your mixture screw set, meaning how many turns out from to lightly seated?

You may want to check it by raising the slide to a high idle, then slowly turning the mixture screw out, 1/8 to 1/4 turn at a time and listening for the idle to climb. Turn the mixture screw back on 1/4 turn, then back out the idle screw until your close to factory idle speed (may need a tach for this), or it's not turning the rear tire or stumbling.

If it still won't idle, maybe you have leaky crank seals. I had that happen on a few scoots and it made setting the idle into a right PITA.

Before you start adjusting the carb take the choke out and check it's not stuck out. That would make it struggle to idle when cold.
Depending on what carb you have the manual should give you a baseline setting for the mixture screw. On Dellorto 17.5 it's 1.5 turns out, on the Webber 12 it's 2.5 to 3.5 turns out.

Manual says idle should be 1800 rpm +/- 100

On a Dellorto the choke should look like this;

Did you get your ET2 sorted?

Here's some more data.. from a similar scooter with a Gurtner carb with same electric choke.
To test it, remove it and apply 12 v to it.. the needle should extend after a couple-3 minutes, as it warms up.
I took mine apart to see how it works inside.
I used my car battery.

It never is.
There is a fairly simple way of determining if the issue is fuel delivery. Does the bike fire and run with starter fluid? If it does, the bike's not getting gas. If not, it's either compression or spark. With a two stroke, it's almost always compression.
What carb did you have and what carb did you replace it with?

My issue turned out to be a dirty carb. Took it all apart, reassembled and started right up. Even with a slightly cracked intake manifold which needs to be replaced. Now I just need to get the mixture corrected once the new manifold is in.

Went from the original Weber to a brand new Malossi purchased from dealer. She'll start and even rev pretty high on regular gas. She won't idle reliably and if I try to ride it she'll cut out along the way.

Malossi doesn't make a drop in carburetor for the ET2. Find out what the part number of the carb you installed is, and it will be a lot easier to sort out.

My mistake. Was a DellOrto. Piaggio part 82666R. Got it from dealer

Did the dealer install it and set it up? It sounds like it's idling off the slide and not the idle circuit.

No. I did it. I think I'm going to have to bring it to them to look at and adjust.

Also, if the bike has been sitting for a while, there might be crap in the gas that got lodged in the jets. So make sure they check that the jets are clear.

Thanks. Carb brand new. Emptied tank, replaced lines and petcock. Fresh gas.

|Unless you take the fuel tank out of the scooter and turn it over, it's virtually impossible to get all the gas out. There is a small likelihood that the jets got clogged with material that was in the bottom of the tank, but it's something people who work on these things for a living have seen before.

Thanks for everyone's input. Finally warmed up here in DC a bit and I had a chance to fiddle with it again. After some adjustments to the mixture and idle speed on my brand new Dell'orto carb, I was able to get it running pretty reliably. Took her around the bock 6-8 time with no stalls at the stop signs. Then took her about 0.7 miles to the grocery store with no stalls. She started right up when I came back out. May still get her looked at just to be safe, but will see how it goes first over the next few rides.

joanofsnark Did you get yours sorted?
It has fuel, compression, spark.. and doesnt start?
I've been noodling with a similar engine..haven't seen a progress report on yours.
As az_slynch reminded, we can help each other by posting findings and results.
(I'll dig more into mine on Wednesday)

Just posted update yesterday. Seems like new carb needed to be adjusted a bit. Mixture and idle. Seems OK now. Going to take her out again today to make sure she's still OK. Realize, though that I replaced nearly everything. petcock, fuel lines, carb, reed valve setup, spark plug, gas, air filter, etc.

Thats great news.
But i was also referring to joanofsnark … the OP of the thread.
😊
I wonder if she(?) got her ET2 sorted out.