Modern Vespa

I have a 2001 and 2002 ET2, both with about 1000 miles. Gently used, but used often (every weekend) from May to October. As both started to develop starting issues, I replaced the fuel tap assemblies. Didn't help. Suffered through last year and this spring I figured it was a fine time for tune ups and also to upgrade the carb and muffler. I picked up the proper 17.5 mm carb for this scooter (the Euro Malossi) and the Sito +. Professionally installed by a Vespa dealer, but we are still having starting problems.

The dealer has attempted to replicate the problem, but states that they have no trouble at all starting / running the scooters. They returned the scooters again about a week ago and we went to use them this weekend and the same problem happened.

Key in, crank the engine and nothing but starter. Twist a little on the gas, and after a few attempts almost a firing of the engine. A few more twists and a few more sputters. Keep this up for 5 minutes and eventually you can coax the thing to start. Once started, you have to tease the throttle - too much throttle and it dies. But once warmed up, runs like a top. It's like the choke isn't working and you have to start it without the benefit of choke - or that the fuel isn't running and it takes forever to get it to flow.

The irony here is the one that was worse before the tune ups / carb change is now running fairly well, while the other that was running fine is now suffering from these issues.

I'm open to any and all solutions, including returning everything to bone stock (ie: Put back the 12mm carb and original mufflers).

Any advice? Thanks!

Perhaps you hit the nail on the head with the choke idea - the ET2 uses an autochoke and it may be bad.

Could be a carb tuning issue - mixture being too lean or rich.

You should verify that gas is getting into the cylinder by looking for a wet plug, and you should verify that you are getting a reliable spark by grounding the plug on the cylinder head and running the starter.

If you have new taps but are getting no gas into the cylinder, your jets are probably clogged and fuel line might be gummy.

If you have weak or unreliable spark your CDI, HT wire, and or cap might be going out.

Most likely it's jets/a fuel problem, since the odds of the CDI or something failing on BOTH at the same time are slim.

Let us know what comes out of these tests!

A little more info is in order.

The plug is new, the entire scooter just went through a Vespa Dealer full-blown tune-up. How does the whole fuel flow work in the ET2? I understand there's no fuel pump, rather it works on vacuum. If I had to guess, I'd say the choke isn't in the default "On" position. I read the post where they give the ET2 manual for starting issues and it explained how the choke is always on until the scooter warms up and the choke retracts. But it's really feeling like the fuel just isn't flowing into the engine until 5 minutes of cranking and it has plenty of gas, everything is clean, there's spark, the fuel tap is new, the plug isn't fouled, etc.

Found this description on a new choke for the ET2:

E-choke PIAGGIO, PHVA/PHVB, multi-plug

The E-Choke is a typical wearing part. It is often defective. A defective e-choke might either result in starting problems with a cold engine or a too rich and thus stuttering warm engine. We can offer you cheap and good replacement for all current original carburetors.

This makes sense to me. Very hard to start when cold, but once it's warmed up it runs fine. If the choke were stuck in the "on" default position, it would start fine and then sputter from being on when warm. But if a choke isn't "On", it can be hard to start the engine but once it's warmed up it runs fine. Feels like the problem... Thoughts?

Hmm, now I'm thinking that maybe the new Malossi 17.5mm carbs came with new automatic chokes already installed... Have to take a look.

Since you have 2 et2's you can test the choke easily enough. Take the choke unit out of 1 scoot, plug it into the second bike, start second bike up. The choke needle should a move outwards @4mm if it's good. Wait for the engine to cool down, switch the choke units, check again.

Also, yes, the new carb probably had a new choke unit on it.