Modern Vespa

Hallo to all. I need help because I am desperate on this topic.
It happening after ride, after few hours of standing after ride.
My Gilera Stalker keep leak fuel from carburetor (Weber OM12). You can see on picture where is location of leaking, where I get flooded air filter inlet and whole carburetor is wet, so it is almost impossible to start it (after some time of pushing it start).
Engine is running excellent when start.
Now, i know fuel should be stopped in carburetor with shut-off valve on float, and also on vacuum valve on tank. I changed tank valve, but it work only month or so, and I get problem again (membrane is not quality obviously). I changed new shut-off valve, but ...
Should fuel be stopped on shut-off valve only only?
Please help, my knowledge end here.
P.S.
In desperation I bought another used carburetor, but same thing happening.

Thanks for any help.
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I would suspect a dirty float needle.

+1

On both carburetors tried two needles + one new. No help.

Float needle or jet needle?

Float needle of course. I bought new one because it was my first suspect, and it was not cheap at local shop.
I made also a test:
I dismount carburetor, put it on flat table (in natural position) and connect piece of fuel hose (2 m length) on fuel connector on carburetor, other end of hose above the carburetor. Pour water in hose and wait few hours. No leak. Then, same carburetor (without water) mount on engine and start it without problem. After few hours there was leakage. Just to mention again that leakage location is only as on picture. And it leak very slowly.
Old trick by mechanic, blowing into fuel connector when carburetor is upside down (float by wight close shut-off valve) also look good, no air is passing trough.

Assume that new tank vacuum valve could help this, but I don't think this is right solution for long run?

Have you tried replacing the gaskets? Might be a small leak through one of them

How frustrating. Been there. Your testing procedures are valid. It would be nice if BOTH the needle and seat were replaceable. A new float needle on a bad seat can't fix it. It's a problem on many gravity feed applications.

Since you said it runs fine after getting it started, an inline mechanical shutoff valve, if it can be installed where you can get to it, could possibly solve the leakage while stored issue. It's sort of a band aid fix, but is used often. It could also deter someone riding away on it.

I would second the shut off valve, it would be a cheap fix you could live with.

I visit local service yesterday and repairman claims that leakage is normal if vacuum valve is not working. Is this true?
Anyway, replaced new vacuum valve on tank and this morning it started like new, no problem at all.
Cost was about 15$. Assume I will have to replace them every year, so be it. Case closed for now. 8)
Thank you all for suggestions.

P.S.
Last vacuum valve purchased two month ago last only 1.5 month.

You tell them it leaks?where you bought it

Well, here is update.
Scooter is in workshop as I don't have any clue whats happening and don't have any nerve to work on scooter any more.
It is leak again after just 4 days of normal work.
As I doubt that service will resolve this problem, I assume that at end it will be best to just replace whole carburetor with new one, so I want to be prepared with some info.
Currently installed Weber OM12, assume is out of production, so what other carburetor is suitable for Gilera Stalker (2000)?

mmmh if the vacuum valvel does not works there is NOT fuel in the pipe or fuel does not stopped.
looks if the gatherer joint to vacuum pipe ( ir , depressor ) is in good conditions, (holes, cuts, fissures), and not bend etc..

seems that the carburettor needs a seals change and a needle change , like was upper suggested.

in next time if the vacuum is easy accesible for you, put a manual version vacuum ( with lever not with knob version).

where do yoi live in Croatia ?

regards from Triest

Thanks for post. I live in Pula, almost neighbors.
Well, as they told me, there is no spares for webber any more.
As there is new vacuum valve installed (after disconnecting tubes it looks like it work OK), I think to buy new carburetor.
http://www.ebay.com/itm/130583279894?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Is this OK for my Stalker?

the carburettor in the auction is a 18mm it is from HK, I have doubt it is a genuine dell' Ortro carburettor ( the carburetor in the image seems to be a chinese cheap carburetor)

this is a genuine ( is quite expensive )
http://www.ebay.it/itm/CARBURATORE-DELLORTO-PHVA-17-5-ED-PER-SCOOTER-GILERA-DNA-STALKER-ICE-EASY-50-/230933666163?pt=Ricambi_e_Accessori_Scooter&hash=item35c4b81973

which is your actual configuration ? ( cylinder, exhaust etc )?

if your scooter has a quite elaborated engine ( exhaust like an expansion etc) I think is better to install a 19mm ( more spare parts)

PS, if you know somebody who come in Triest for shopping, send them to " GS Motoricambi" ( via XXX ottobre 11) or to " Motocharlie" ( via Valmaura ) shop a lot of people from Histria came in this shop for spare parts ; where there are attendents who speake croatian too . A real good assorted genuine or compatible, spare parts shop . I go in both shops when I need .

I don't know any numbers about my setup, but I think it is original (as I am not first owner).
I'd like to keep original setup, because I don't have time or interest for customization. Just want to work as it should. I am not young any more.

Well, I visit TS sometimes, but Croatia is now part of EU, so there is no more tax free.

Now, I really considering idea to sell this and make upgrade to Beverly 250.

Have you checked to make sure that the float itself isn't leaking? A leaking float wont float properly and the ethanol in fuels doesn't help. You might also check your float valve to make certain that it is working properly. I recently had an issue sort of like yours with a Sherco trials bike and a Dellorto carb. I must have taken it a part a million times only to realize that the hinged bar on the float that activates the float valve was slightly tweaked. After gently re-tweaking it, all was well. Issues like this can be frustrating, but if you look through it step by step, the problem will rear its head. Good luck.

this is a good suggestion, happens that the head of the needle do not works properly.

Mr Opus : maybe the needle needs just to be clean ( the "gummed" head) or changed and the float pivot maybe do not works..

in 2 strokes engine carburettor the problems usually are very simple to solve, maybe just some dirty somewhere..

PS : Croatia is not part of Europe ? You are so LUCKY !