Vespa does not start without giving it gas
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2016 Piaggio Primavera 50cc
Joined: 08 Sep 2020
Posts: 3
Location: Miami, FL
Tue Sep 08, 2020 5:04 am quote
Hi,

I am new to the scooter world. I bought a used 2016 Primavera 50cc. I did not ride it for months and did not start it during that time. I did have trouble starting last week and eventually after twisting the throttle before starting it finally started but died after giving it gas; on another attempt it idled high before idling low and dying. The next day I did the same thing but took off while it was still idling high and that day I had no issues. The Vespa sat for two days and when I went to start it it wouldn't kick over unless I gave it a little gas. I was wondering if anyone would be able to steer me in the right direction before taking it to mechanic. Do you think it needs a carb clean or could the gas be old (at least 6 months) or something else? My guess is I shouldn't have to give it gas to start the scooter.

Thanks!
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Bashan 150, CF Moto Fashion 250
Joined: 07 Dec 2008
Posts: 943
Location: Hyde Park, New York
Tue Sep 08, 2020 6:18 am quote
Throw a cap full of Seafoam in the tank and ride it. There could be some ethanol crud over the idle jet. Time, miles and Seafoam may clear it up.
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2016 Piaggio Primavera 50cc
Joined: 08 Sep 2020
Posts: 3
Location: Miami, FL
Tue Sep 08, 2020 9:13 am quote
Roger that. I will give it a try and send an update.
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BV 350
Joined: 22 Nov 2016
Posts: 677
Location: Nebraska
Tue Sep 08, 2020 10:49 am quote
How many months
Modern fuels, especially those with ethanol, can go bad in a month or two. You can avoid that with Sta-bil or other fuel stabilizer. If you didn't use one, I'd say siphon out as much gas as you can, replace it with fresh gas, add a little fuel system cleaner, and you should be fine. Without replacing the fuel, you might find that it runs pretty crappy until you put fresh fuel in.
Member
Joined: 15 Jul 2020
Posts: 14
Location: Brea, CA
Tue Sep 08, 2020 11:03 am quote
I think this is because your vespa fuel tank contains old gas.
My vespa did same when I try to start after a couple of weeks, it's start after few attempts.
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2016 Piaggio Primavera 50cc
Joined: 08 Sep 2020
Posts: 3
Location: Miami, FL
Tue Sep 08, 2020 2:47 pm quote
Re: How many months
Jimding wrote:
Modern fuels, especially those with ethanol, can go bad in a month or two. You can avoid that with Sta-bil or other fuel stabilizer. If you didn't use one, I'd say siphon out as much gas as you can, replace it with fresh gas, add a little fuel system cleaner, and you should be fine. Without replacing the fuel, you might find that it runs pretty crappy until you put fresh fuel in.
Thanks "Jimding"
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Lx 50 4T, GTS 250, S 150 (Missing in KS), Something Chinese, GT 200 (sold)
Joined: 21 Feb 2011
Posts: 8825
Location: KS USA
Wed Sep 09, 2020 4:22 am quote
I had the same thing happen to my Lx 50 when I bought it a couple summers ago. I also removed the carb and sprayed that as much as I could. I didn't actually disassemble the carb. Just put it back on the scooter after cleaning it cursorily.
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2008 MP3 500, 2013 BV350, 2020 Vespa Sei Giorni
Joined: 13 Oct 2012
Posts: 8635
Location: Ashburn, Va. Home to the Internet
Thu Sep 10, 2020 8:09 am quote
Pull the carb and clean it.
Seam Foam is a Very very weak cleaner that isn't going to do anything. If it had anything to it you wouldn't be adding it every tank full.

Take the carb off and clean it.

You want a good carb cleaner use something like BG44K or Chevron Techron Concentrate Plus Complete Fuel System Cleaners.
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Lx 50 4T, GTS 250, S 150 (Missing in KS), Something Chinese, GT 200 (sold)
Joined: 21 Feb 2011
Posts: 8825
Location: KS USA
Thu Sep 10, 2020 8:15 am quote
WEB-Tech wrote:
Pull the carb and clean it.
Seam Foam is a Very very weak cleaner that isn't going to do anything. If it had anything to it you wouldn't be adding it every tank full.

Take the carb off and clean it.

You want a good carb cleaner use something like BG44K or Chevron Techron Concentrate Plus Complete Fuel System Cleaners.
This not always necessary. What I did was enough and never had problems since.
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Granturismo 218
Joined: 04 Feb 2013
Posts: 6320
Location: NWAOK
Fri Sep 11, 2020 7:59 am quote
Re: Vespa does not start without giving it gas
jjoneil wrote:
Hi,

My guess is I shouldn't have to give it gas to start the scooter.

Thanks!
If you have to give it gas to start the scooter, that's the wrong guess.
Mechanical issues require mechanical solutions, and no magic potion is going to change the settings of your carburetor. The people who believe these magic potions work tend to be the ones who have the most issues with fuel delivery in their vehicles, blame ethanol for all the woes in the world, and have the least amount of understanding as to how the system is supposed to work. Back when carburetors were common, people used to pour diesel down the carburetor while the engine was running to clean it out. You can try that too. It also won't fix your problem.
This engine was designed to run on gasoline, or gasoline and ethanol. It was not designed to run on any of the mechanic in a bottle potions you have been told to add to the tank. The manufacturer knows gasoline contains ethanol, and builds the fuel system accordingly.
The opening in the pilot jet, or idle jet, in the carburetor is miniscule, and if it clogs, you will have issues. If you add something to the gas that somehow manages to break down any buildup in the tank or bottom of the carb, there's a better chance that some of that material will end up in the idle jet than that it will clean and repair your fuel system.
Also, gas formulations change in many areas throughout the year, different gasoline refineries use different additives, the weather changes, etc. All these are things a fuel injection system can adjust for, but the carb can't. So you might have to give it a little gas to get it started at some times, but not others.
And there's an excellent chance that the air/fuel screw was never set properly.
If the gas has sat in the tank for six months, it has probably evaporated in the carb during this time, and that is not good. Depending on how much fuel is in the tank, you can either add to it, or drain and replace. Under a quarter tank, I would top it off with fresh gas, otherwise, remove and replace.
If the carb has sat for six months with gas in it, and you clean out the jets and it still doesn't run right, but the fuel valve works, you will need a new carburetor. That's pretty much how things work with the 50cc four strokes.

And for everyone getting ready to park a carbureted bike for the winter, DRAIN THE CARBURETOR BOWL.
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Bashan 150, CF Moto Fashion 250
Joined: 07 Dec 2008
Posts: 943
Location: Hyde Park, New York
Fri Sep 11, 2020 8:35 am quote
He said the scooter starts with a little throttle and then runs fine for the rest of the day. That's a tiny problem and if it was me I wouldn't give it a second thought. A little Seafoam or fuel system cleaner is a mild fix. I have had bikes that ran a little funky in the morning for no apparent reason and then cleared up after an hour or so. Carburetors are a little fussy sometimes and you just have to humor them. Taking them off to clean them for a tiny problem is a little like overkill and opens up the possibility of causing an even more annoying problem later from all the hoses and gaskets you've disturbed.
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GTS 250ie Super, Italjet Velocifero, Scarabeo 150, S50,ET4
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Location: Winston-Salem, NC
Sat Sep 12, 2020 3:16 pm quote
Listen to Motovista he knows about carbs and scooters. I have had a number of scooters with hard start issues and giving it gas sends a little gas in through the accelerator pump and it starts. Holding it open takes it out of the idle circuit so it will run. I have always solved the problem with being sure the enricher is doing its job and making sure the idle jet is doing it's job. The idle jet has to be perfectly clean to function. Unless Seafoam has a tiny submarine with scrubbers on it like "The Incredible Journey" then it won't replace a wire run through the idle jet to clean it. Once you KNOW the jet is clean then adjusting the A/F mixture will get the idle in proper tune. I have had a partially clogged jet that I adjusted for with the A/F screw until I had the chance to properly clean it. Please stop recommending snake oil to do the job that needs to be done physically.
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Lx 50 4T, GTS 250, S 150 (Missing in KS), Something Chinese, GT 200 (sold)
Joined: 21 Feb 2011
Posts: 8825
Location: KS USA
Mon Sep 14, 2020 9:25 am quote
Pinkscooter wrote:
Listen to Motovista he knows about carbs and scooters. I have had a number of scooters with hard start issues and giving it gas sends a little gas in through the accelerator pump and it starts. Holding it open takes it out of the idle circuit so it will run. I have always solved the problem with being sure the enricher is doing its job and making sure the idle jet is doing it's job. The idle jet has to be perfectly clean to function. Unless Seafoam has a tiny submarine with scrubbers on it like "The Incredible Journey" then it won't replace a wire run through the idle jet to clean it. Once you KNOW the jet is clean then adjusting the A/F mixture will get the idle in proper tune. I have had a partially clogged jet that I adjusted for with the A/F screw until I had the chance to properly clean it. Please stop recommending snake oil to do the job that needs to be done physically.
This^^^
Enthusiast
2014 lx50. 4t
Joined: 08 Aug 2020
Posts: 97
Location: Lorton virginia
Tue Sep 15, 2020 8:37 am quote
My owners manual says when starting twist throttle a little. (2014lx) My 2016 does not say to turn the throttle a little. Both are carbs. Both scooter will start without touching the throttle and keep running
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