Modern Vespa

I've upgraded my 2001 ET2 over the past 4 years, but barely ridden it (50-100 miles). The last I rode it was nearly 2 years ago. Finally living in a city again! Whoo!

I can get it started after laying on the ignition for ~30 seconds or so. I have to pump the fuel, and keep it cranked fully open to get it going, but it hits idle and stays there no problem. It also runs/drives really well- no issues.

It will restart immediately with no issues if very recently turned off, but after 10 - 30 minutes I'm back to the same issue.

Fuel is new.
Oil is full.
Spark plug is new.
Battery is new and fully charged.
Carb was recently cleaned.

Smart Scooterists...Any ideas what might be happening here?

The sound it makes when it doesn't want to start, sounds as though it doesn't have enough fuel at the cylinder. There are no visible cracks or punctures on the "suction line" from the fuel tap.

Lots of new/upgraded parts in the past 4 years including:
- Fuel tap
- Malossi 70cc Cylinder
- Malossi Multivar Variator
- #80 main jet for carburetor
- oil pump belt
- CDI spark plug cap

LISTEN to an audio recording of initial startup, run, then turned off and immediately restarted. http://tru-tone.com/wp-content/uploads/2022/Vespa-ET2.mp3

Thanks for any insight!

Pull the plug - that will tell you what you want to know. 2 strokes don't need a lot of choke to get going. The key is getting the jetting and idle mixture right.

You don't list new fuel and vacuum lines - they are the usual suspects. And clean the carb again, paying particular attention to the fuel inlet needle. The shaft of a pop-rivet is a useful tool to gain access to it.

What sort of carb? That's a big main jet for a dellorto on an et2 70cc scooter.

You could not just leave it alone? What did you gain by the mods? It is a fifty cc two stroke you should have left it alone short of an exhaust. I put an after market exhaust on my ET2 from Scooterparts.co now going about 48MPH.

Thanks everyone for your time and input!

The fuel, and the fuel lines, along with the tap are all new. I remember when I first bought this new from the dealer, I had the same problem for a few years. They just kept replacing the fuel tap. Eventually the dealer put in a whole new engine. I don't really know what the issue(s) were then.

The carb was just thoroughly cleaned, but I'll take a look at the inlet needle.

My guess is whatever is going on here is at least partly related to it sitting for a little more than a year (no fuel was left in it during that time).

I will also pull the spark plug today. Thanks for the suggestions Tierney. Any pointers for what I am looking for? The current plug has nearly no hours on it.

These and other mods were made, including a Tecnigas Silent Pro exhaust based on information marketed for the ET2 at more than one popular online scooter shop, along with user experiences found in these forums, with the goal of adding a little more acceleration zip, particularly when carrying a passenger. It's definitely achieved that, and runs better than it's ever had. I've put a ridiculous number of miles on this thing when I lived in Chicago and have emotional attachments to it explaining why I haven't just swapped for a whole new scooter yet. I've certainly spent the money to have done so.

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Hiya.

A few things - have you inspected your air filter? They can break apart if very old, and chunks can get sucked into the engine (not happened to me personally though). Also check the rest of the air intake is clear (including that convoluted air inlet that starts just above the curry hook).

As stated above - it's good to know whether you're running the little Weber carb, or a larger 17.5mm Dellorto - jet numbers are different for each. I have a Malossi 70cc cast iron kit, and on my 17.5mm carb the main jet is most certainly not as high as 80.

Also, petcock + fuel + vaccum lines. Make sure they're clear and well sealed. Ps just because your petcock/lines were new a few years ago, doesn't mean they're ok now. Stuff like that can perish.

You can also check your 'auto choke' if you have one. Could it be stuck? If using a manual choke, make sure it's operating properly.

Also, may as well check your CDI's earth connection just in case & HT lead etc. Stuff can corrode.

Thanks OscarSass!

I had to dig back through my files and communications with Scooterwest.com Based on the upgraded cylinder they also sold to me, They recommended and sent me an #80 jet, so that's what I installed.

No issues at all once it's running.

Fuel + vacuum lines feel/appear to be in great shape, but even with the zip tie, the vacuum line can swivel if handled. Maybe that should be tighter/replaced.

The air filter is also recently been replaced.

Good suggestion on the choke. I'll check that.

I think you have the original Weber carb then - stock size is 76, so it makes sense to have an 80 after installing a big bore kit, especially if you got Sooterwest's input.

So... I hadn't considered this:

I just moved from the midwest (~600 ft elevation) to Utah (~4600 ft).

From what I've just read, I should probably re-jet down 4 sizes from my #80, back to the stock jet of #76

Update:

Pretty sure the culprit is either the fuel tap or the vacuum line. The line looks and feels like it's in good shape, and the fuel tap is newer (but I've had problems with this part before). Might just replace all of it to be sure.

Then when I started the scooter. Same problem struggling to turn over for 15 + seconds. THEN, when it did, it sputtered fuel from the exhaust.
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Once I found my spark plug wrench, I discovered the new(ish) plug to be blackened. - Good suggestion Tierney. I installed a new spark plug, but will need to fix the fuel issue.

I checked the air filter. It's still in new condition, and not saturated, only very lightly / evenly

You'll also want to check the e-choke is functioning properly else you can still run overly rich.

How far have you ridden the bike so far? Just wondering.

You'll only know everything is as it should be once the bike is fully warmed up (especially with an e-choke).

Faulty Fuel Tap

Thanks again for everyone's help!

Starts right up now. Runs great.