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2003 Vespa Granturismo 125
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2003 Vespa Granturismo 125
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Location: Birmingham
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Yes, you read the subject right, my et4 farts, which while amusing causes it to stall until it has "passed wind" and then runs till it needs to fart and stall again

I have a 2001 et4 125, this is a uk one so the evap hose system isnt there (you have no idea how many problem solving posts revolve around this)
When I first had it, it ran hot, from my previous vespa px knowledge, I presumed I had a bad fuel flow causing not enough lubrication and a hot engine. So I investigated the fuel tap to find the bloody thing was in fact stuck open partly and couldn't do its job.
I also noticed the carb maifold had a crack so both these items were changed for new.
For a few hundred miles it ran perfectly, then the bad starting and stalling started to happen. you'd hold the brake and press the electric start button, the bendix engaged and spun the variator but it wouldnt start till it farted! soon as it shot a blast of air out (from the airbox usually dislodging the under seat air hose) it would run great for a few miles until it stalled again whilst stopping for lights or a junction at which point made the engine sound like it was blowing bubbles as the air built up ready for another fart.
As soon as enough air builds up, my et4 stalls, some days you cant open the throttle more than 1/8 unless you want to stall, and when starting sounds like a co2 pistol firing a couple of times before it starts.

What on earth is causing this air build up? I cleaned my carb and jets, my airbox and air filter are clean and my tank has been cleaned out. Any ideas would be much appreciated, apologies for the waffle but I'm trying to give as much info as possible. Thanks in advance
@gasmk1 avatar
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Vespa lxv 125 vie dell moda Chianti
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@gasmk1 avatar
Vespa lxv 125 vie dell moda Chianti
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Is there a breather on the petrol cap ? If so could this be blocked.
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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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If you're sure everything external is hunky-dory, I'd advise checking the valve clearances, and also checking the valves aren't sticking. Worth doing every few tens of thousands of miles anyway.
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Molto Verboso
lx150
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lx150
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Sorry, I can't stop laughing. I wish I could offer help.
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2003 Vespa Granturismo 125
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Update: firstly thank you for the helpful replies, as of now I have changed the following:
Spark plug
Carb manifold
Petrol tap
Automatic choke
All the jubilee clops on the hoses
A new belt (on inspection the one I had was about to split in 3 places)

Fired her up after changing the parts and she wasnt happy. Ive never had to twist the trottle to get her going before
I checked the spark plug cap and found it was a little loose. A quick adjustment and she fired up

The first 10 miles after doing all this, the et4 ran a treat without a single toot or spot of flatulence. Next day however the gaseous girl was back to her old tricks.

Now the valve lash gap.... I had set this myself just before I changed the parts above. The intake valve was a doddle however the exhaust valve was a little different. I rotated the chain to the 2 valve spot and checked the gaps to find both were well looser than necessary. The exhaust valve had a little play in it which made it hard to set. Totally different in feel to the inlet port. Could this be the problem and what can I do to loosen the sticky valve? Didnt want to spray some air lubricant willy nilly in my engine.

Have also just ordered a new coil just in case the spark system is causing the agro as fiddling with that seems to make the best result
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2003 Vespa Granturismo 125
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Gasmk1 wrote:
Is there a breather on the petrol cap ? If so could this be blocked.
Thanks for the idea, but my petrol cap isnt vented should it be?
@jimc avatar
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The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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@jimc avatar
The Hornet (GT200, aka Love Bug) and 'Dimples' - a GTS 300
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guyr3tr0 wrote:
Gasmk1 wrote:
Is there a breather on the petrol cap ? If so could this be blocked.
Thanks for the idea, but my petrol cap isnt vented should it be?
Cap no, but there should be a breather tube just a few cm down inside the filler neck. This tube may be blocked. Spiders etc. A long shot though.

If you think you have a sticky valve (and I had a couple on my GT200, as found out in Italy returning from Greece) then replace the valves and O-rings etc. Cheap enough in parts as long as you DIY.
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Peugeot Citystar 200i, Vespa PX 200
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Thanks for the hilarious post! Sorry I can't be of any help but you just saved my day.

Reminds me of this
Quote:
He was famous for his remarkable control of the abdominal muscles, which enabled him to seemingly fart at will. His stage name combines the French verb péter, "to fart" with the -mane, "-maniac" suffix, which translates to "fartomaniac". The profession is also referred to as "flatulist", "farteur", or "fartiste".
Your lady on two wheels is a fartiste!
⬆️    About 1 month elapsed    ⬇️
OP
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2003 Vespa Granturismo 125
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Location: Birmingham
 
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2003 Vespa Granturismo 125
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UTC quote
jimc wrote:
guyr3tr0 wrote:
Gasmk1 wrote:
Is there a breather on the petrol cap ? If so could this be blocked.
Thanks for the idea, but my petrol cap isnt vented should it be?
Cap no, but there should be a breather tube just a few cm down inside the filler neck. This tube may be blocked. Spiders etc. A long shot though.

If you think you have a sticky valve (and I had a couple on my GT200, as found out in Italy returning from Greece) then replace the valves and O-rings etc. Cheap enough in parts as long as you DIY.
thank you jimc, however it is the actuator arm that is sticky rather than the valve itself.

She's actually got worse now, idles terribly and you have to have the idle screw wound all the way in. I dismantled the carb and thoroughly cleaned to find there was grit in the idle jet but clearing this made no difference.

someone suggested a blockage in the exhaust causing the flatulence problem? what does the exhaust valve actually do please?
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Scooter Pimp
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@fabio_dougie avatar
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I'm not an expert on the ET4 by any means...but here is what I'd try first before I replaced vales / lifters.

You said that when you were trying to set the valve gaps that the exhaust valve had play, it makes me ask how many miles has the engine done?


Here's what I'd try....

What is the level of the engine oil?

On some engines (not necessarily Piaggio) low oil levels can cause lifters to click. Too high oil levels can cause air bubbles. Again this is just general engine problems so may not apply to the ET4. What is the level and condition of your engine oil....also what viscosity grade is it?

Then If this doesn't help, the next thing i'd try is to get hold of some oil additive like Forte Valve Cleaner...what you do is add it to your oil and then get the engine nice and hot, then drop the oil and refill with normal oil. Hopefully a mildly sticking valve or lifter should right itself after this.

If not then finally what I'd try is to remove the valve cover and soak the valve stems in penetrating oil and leave to soak in, some *gentle* taps with a hammer may just loosen.

If not then its back to JimC's recommendation of replacement

Hope this helps (and again I apologise if its not relevant to the ET4 engine - its just some general engine tips I've picked up over the years than may help)

Fabio

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Veni, Vidi, Posti
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Veni, Vidi, Posti
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I had a scoot once that would fart as you say, and it turned out to be too much unburned fuel in the exhaust pipe brought on by a dodgy carb. It would then ignite in the hot pipe In your case, I would check the choke system as it sounds like you are getting too much fuel, that is, the choke is stuck open or the choke system itself is dirty. I know you replaced it but there may be some smarf in there that is stopping it from operation properly. Pull the plug after trying to start - betcha it is dirty and wet. Put in a new plug and check the ends and wire. Good Luck.
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