Modern Vespa

Help needed. I have a 2001 Vespa ET2 2 stroke with flooding problems.
First I will describe the problem, then I will state what I have done to attempt to fix it.

I recently bought this vespa with 485 miles on it. Very hard to start, usually takes 50 or so kicks with the throttle wide open, it then starts and once cleaned out, runs great! I can ride it for hours with no problems. If I turn it off, then wait 20 minutes or so, it will be flooded again and after 50 or so more kicks, it starts up, clean it out and ride again as long as you want. If parked overnight there will be a fairly large stain on the ground where fuel has leaked out onto the ground. It is coming from the airbox and running down the variator cover. I will lose 1/4 amount or more of fuel if it sits for a few days from leakage.
Runs great, idle is perfect, acceleration is awesome and top speed on flat ground is 43 MPH (70 KPH)
What I have done
1: cleaned the carb, checking the needle. no luck
2: Replaced the needle with a new one, no luck
3: Checked the fuel tap, was bad as fuel continually poured out of the clear fuel line once disconnected from the carb.
4: Replaced fuel tap with a new one, no luck
5: disconnected the clear fuel line from the carb, drained the gas out of the line, reconnected it and waited until the next morning, had fuel in it. (I never spun the motor over after clearing the fuel), Thought the fuel tap had a small leak, replaced it again, no luck
6: noticed there was no gasket on the fuel cap, Thinking that an air leak may cause fuel to flow from the bottom of the tank (Like a water bottle for a hamster), I made a gasket from an inner tube until I can find a new original one, No luck again
7:I also replaced the spark plug with a split fire (Nice plug!)

My next guess is to replace the float in the carb. What is it gong to take to stop this thing from flooding? It is a Weber carb. I am thinking either the surface that the needle seals on is bad, or the float is not raising up to shut off fuel flow. Maybe that's why it has low mileage, not running correctly from new?

Once started and cleaned out, it runs and idles great!


I have been kick starting it, the electric start does work, but I don't like to wear the battery down. I do use the electric start to re start it after sitting less that 10 minutes.

Any advice is appreciated. Fabio, especially yours

Second question is: There is a plastic shield around the cylinder, from that is a black rubber hose that goes within an inch or two from the carb (roughly 30mm diameter), but is not connected to anything, mine is missing, what does it do?

Hi,
Your auto choke has failed, when they fail the choke fails on, make sure you have a 12v supply when the ignition is on to the auto choke.
Cheers Andy

I had a similar problem a while back, and when I ordered a replacement float needle the parts I received were the needle, needle seat and "O" ring. My Haynes Manual for your model specifies a float height of 3.5 mm, but says that this is not adjustable.
Andythebuilder is right in stating that the autochoke will fail in the "choke on" situation, but from memory (and feel free to correct me) I seem to remember that that it is fed directly from the stator, so you won`t get a voltage to it unless the engine is running.
To check the autochoke is working, remove it from the carb., and when cold measure how far the plunger extends from the body of the unit. Apply a 12v feed and return to the terminals, and the plunger should extend away from the body. Disconnect the power, and the plunger should retract to its origional position.

Hi tony,
I agree with hexaatony on checking the needle and seat,the float height but on a 2t and 4t the choke IS operated by the ignition and not the stator, the stator is a.c and is governed directly by the voltage rectifier only the headland is run directly from the stator on the 2t only.
Cheers Andy

Thanks for the info, Ill check the auto choke. It seems that if the choke were stuck in the "On" position, that it would run rich (Which it doesn't seem to do), also how would this effect the leakage when it sits overnight? It starts very hard when cold as well as when it is hot. If the choke was on, wouldn't it start easy when cold?
Additionally, I don't see any adjustment for the float, but heard that sometimes they twist over time (My local vespa dealer told me that)
One more thing, I did replace the needle that inserts into the float, but didn't see a way to replace the seat, I thought is was a machined surface, can you confirm that there is a seat for the needle to seal on when the float raises the needle?
I'll check the auto choke and post the results.

Hi buddy,
You could stop wasting time and money chasing your ass trying to fix it,
Fit a new 19mm carb around 30 bucks straight swap no messing and the added bonus of snappier acceleration and a higher top speed.
Cheers Andy

Andy,

I did consider replacing the whole carb as you suggest, My local Vespa dealer wants $189.00. Are you referring to a Chinese carb? I have no experience with them and a little hesitant. Do you have a particular model you would suggest? I like your idea to replace the whole thing..
Any info on a direct replacement would be great!

Hi buddy,
Follow this link
http://www.pedparts.co.uk/bikes/-piaggio/zip-50-2-stroke/carbs-carb-spares-jets?
All pvhb 19 mm round slide carbs are about the same in terms of sophistication and manufacturing, it's not high precision high end performance parts.
Other than branded names eg dellorto, all the rest look identical and are manufactured in Thailand or China .
The link gives you an side of what's look for your side of the pond.
Cheers Andy

Ok, I took the carb off my sons Et2, Put it in my Et2 and the problem was cured. This tells me this problem is carb related. I did not swap the choke when I switched carbs, so the choke is not the problem. I will swap the float in the carb tomorrow and hopefully get this figured out.
I will post updates to help others with this same problem.
Any advise with this problem is appreciated.

OK, Worked on the Vespa AGAIN today. I took both carbs off comparing every part. From what I can tell, the "seat" in the carb that the needle seals off on when the floats raise the needle to shut off the fuel is bad. The good one has a nice finish at the bottom of the hole where it seals on, the other one (mine) looks like an EDM finish (Lots of craters) and not a machined finish. The seat is an insert, but my local dealer says it is not replaceable. I seem to believe them because there is no way to get the insert out.
I don't want to try to refinish it because I will need to go deeper with it and I don't know how much I can take off and still have enough for the needle to toch and seal it.

So, I am looking for a replacement carb. Can anyone confirm exactly what I need? From what I have looked up, The Weber I currently have is a 12mm, Then there are letters that I don't understand. (PHVA,PHBG etc..) I need to understand what I need in order to order the correct carb. I know I need a 2 stroke carb with oil injection, I need a vacuum port for the fuel tap, a fuel in and preferable an electric choke. Then I need to make sure that it still connects to the air filter inlet and the intake.
If I increase the size to a 17.5 mm, I still need these features and I need to know if the jets are readily available. (Are all jets interchangeable between carbs of this size?)
Sorry for the long post, But I want to make sure I get what I need

Hi

The original is probably a Weber 12

I'd swap this for a Dellorto PHVA 17.5 - improved performance - for little cost.

Try a second hand dell'orto carb from ebay/similar.

Fabio

In my et2 there is a Dellorto PHVA. (To the later models Piaggio put this.) I would buy a new original 12mm one. In my country it's only about 70$.
http://sracing.hu/uzemanyagrendszer_86/karburatorok_67/karburator_dellorto_12mm_phva