Vespa LX Carburetor Jets Cleaned
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2007 LX 150 (RIP); 2007 GTS 250
Joined: 12 Jul 2011
Posts: 29
Location: Charleston, SC
Wed Jul 02, 2014 7:39 pm quote
Jimi257 wrote:
Hopefully I can fix the wife's 2007 LX 50 today & be the hero. Darn thing won't start, having been totally reliable up to the point of leaving me stranded on the roadside last week. I've been doing a whole lot of Vespa wrenching lately (for me.) Just tackled full service (belt, rollers, oil/filter, air filter, spark plug) for the first time on my GTS 250. A lot of work, but I'm glad I tackled it.

I have the LX cracked open at home right now in an attempt to pin down the problem that caused me to get stranded in the heat last week and what's keeping it from starting. I've cleaned the bendix as well as I could--I think a bodybuilder torqued the variator nut down last time because I couldn't get it off with my 18v impact wrench or with a torque wrench & a towel (I don't have the variator tool for the LX50, so I used the rolled-up towel trick...which totally worked on the GTS, but did nothing but shred the towel on the LX's razor-toothed gears. I had been hoping that it was just the bendix and was not to be thwarted, I covered the belt with the towel & sprayed the gear assembly with WD-40 and then wiped it down the best I could. I then placed the cover back over the transmission housing & tested the ignition. The bendix engaged & turned over the engine, which was an improvement. Repeated attempts yielded no ignition. I removed the spark plug lead and reconnected it (after was unable to get in to remove the spark plug. I picked up a double-drive extenable ratchet set on clearance at Lowe's...looks like it make getting at the spark plug a bit more manageable.

I even removed the top casing of the carb and cleaned it out as best as I could...but I didn't know how to proceed further with it, so I put it back together. I went to bed, got 1 hour of almost sleep and went to work. I'm about to get off, go home, take a nap and then we're gonna clean that carb out. Here's hoping this takes care of the non-starting problem! Time to go...exhausted. Glad work is only 2.5 miles from home.
So, to follow up in case anyone wants to know, I did disassemble the carb & put it back together. I believe I found a small clog in one of the jets, which I blew out with air. Unfortunately, that didn't resolve the problem. A trip to the shop concluded with replacement of the CDI. Everything's groovy now.
et4 150
Joined: 16 Jul 2014
Posts: 2
Location: Long Beach
Sat Jul 19, 2014 11:44 am quote
Hey Long Beach!

I am about to do this project, and was re-reading this whole thread and noticed someone said something about Long beach. I hadn't even noticed the writer of the post (you) is named Long Beach.

Well, I am both a recent newcomer to both Long Beach AND Vespas. I would love: 1) any advice on this Italian thingy. 2) to ride sometime IF I ever get this thing running correctly. I have been a BMW rider for the past 9 years, but finances have forced me to try more affordable modes of transpo.

I recently got an ET4 150 for what I thought was a good deal. It ran great at day of pick up, but I proceeded in my ignorance to top off the tank several times over the next few days. I also found the evap hose disconnected and thought I was fixing it by putting it back where it is supposed to go. I now have severe hesitation, and misfiring. I have found and read, but do not fully understand the blue key / red key CDI thing. It feels to me like a spark issue, and the CDI might be the problem, but how could overfilling cause that? I have removed the charcoal can and it did not contain any wet gas, and hardly any gas vapors. I managed to get a new spark plug in.

It starts easily, but misfires with throttle. After a few minutes running it usually begins firing smoothly and consistently if I give it just a little throttle. If I twist it, it misfires badly and lunges and flattens, lunges and flattens. No fun. The first day, before filling up, it ran great on the highway, 65 on flats, 70 downhill, 55 up hills. Now I can only achieve 60 if I hold a tuck (no bueno), and concentrate on finding that sweet spot on the throttle where the spark or the carb work best.

I know now that I overfilled it several times, but taking the evap hose back off has done nothing to improve it. Could overfilling contribute to jets becoming clogged? I will go ahead with the carb cleaning if for no other reason than to rule it out as the culprit, but I have little hope. it really feels like a spark issue to me.

Please ring me if you feel like overseeing a newb over his head in Italian Engineering. I also am wondering if there is a slight chance of you having a few excess scooter parts. Bobby (Long Beach) 323.369.3389
2010 LX150
Joined: 16 Aug 2014
Posts: 22
Location: Santa Maria, CA
Fri Jan 02, 2015 6:34 am quote
This a good thread to follow when I change to the larger jet in my LX150. Thanks!
'02 ET2
Joined: 05 Nov 2014
Posts: 3
Location: Mills River,NC
Sun Feb 08, 2015 2:07 pm quote
Thanks for all the very helpful information.
Joined: 21 Apr 2014
Posts: 295

Wed Apr 22, 2015 9:08 am quote
Supplemental suggestion . . .

Scrape/file any carb outlet casting bumps and lightly smear some silicone grease (Ace Hardware plumbing department) on the carb and rubber intake manifold join surfaces to deter vacuum leaks . . do NOT use RTV silicone sealer. To maintain rubber suppleness, spray some Armor All (or similar product) on a foam craft brush and apply to rubber CV carb diaphragm, intake manifold exterior, and tire valve stems . . DO NOT APPLY ON TIRES OR SEAT!

Joined: 25 May 2015
Posts: 7

Mon May 25, 2015 11:08 am quote
I was not able to remove any of the screws in step #6 (my 2006 carb has 4) either with a screwdriver or pliers. Either way I chew the metal. This is after spraying with PB and letting it sit for several minutes. Ridiculous. I have removed the carb and still cant get any of the screws off.
Joined: 25 May 2015
Posts: 7

Mon May 25, 2015 11:50 am quote
I was able to get the bowl screws off with a hammer and chisel. Once I got one loose the others were a little easier... but all four required hammer and chisel to get started. More ideas at
shopping for one now :D
Joined: 08 Jan 2016
Posts: 229
Location: Toronto
Mon Apr 04, 2016 5:32 am quote
thanks for the Post!!! great how to

two myths I will clear up:

1) Seafoam is good for your engine - NO! heavy duty solvents etc. avoid.

2) Armor-all good for rubber? no way - armor-all actually dries out plastic and rubber over time. All the real professional detailers avoid it like the plague...
Joined: 05 Sep 2012
Posts: 16
Location: baltimore md
Sun Jun 12, 2016 10:27 am quote
thanks for the detailed instructions. she runs like a top now. it would have taken like 15 min if it were not for those pesky screws on the bottom. that took like an hour.
2012 Vespa S50
Joined: 19 Jun 2012
Posts: 188
Location: South Florida/Macon,GA
Tue Jun 14, 2016 6:49 pm quote
Very well done. This article gave me the kickstart to clean my jets today. Previous poster I correct, this is the second time i semi stripped the screws taking precautions to not do so. The mechanic shop over tightens I think on purpose , so I went to the hardware store and got the proper sized screws with a deeper head so this won't happen again. That's my two cents to those who want to work on their own carbs.
Joined: 05 Sep 2012
Posts: 16
Location: baltimore md
Thu Jun 16, 2016 3:36 pm quote
I had to clean the jet again. It wouldn't start after sitting for a few days. I suspect the extra seafoam I added before attempting to clean the jet is what caused it to clog again. One question is how large is the opening supposed to be. When it's "clean" I can only see a pinprick of light. I have not been able to find a wire or needle small enough to run completely thru. Is the jet tapered on the inside as compared to the two openings on the end?

Joined: 25 Jul 2016
Posts: 1

Mon Jul 25, 2016 9:08 pm quote
Thank you
Just a quick note to say thank you for the great tutorial! I'm a recent new Vespa owner. Just bought a 07 with 300 miles. Would not start. changed the gas and cleaned the jets and I'm off and running. VERY helpful!

ET4-150 (2004); LX50 (2007)
Joined: 19 Oct 2012
Posts: 6
Location: NJ/NYC
Sun Sep 18, 2016 11:04 am quote
What about the jet itself?
Excellent article. i had the same issue/complaints/successes as most people here when I did my 2007 LX50. My carb/jet was 100% identical to all steps and pictures in the original posting.

I have a question/observation:
I found a wire thin enough to fit into the top and bottom openings of the jet, but it would not slide all the way through the jet. However, if I blew air though the jet, it would come out the other end of the jet, as well as the tiny holes on the SIDE of the jet.
My question: SHOULD i be able to push a small enough wire all the way through the jet OR is the jet designed in such a way that gas/air can pass through it, but there is some type of internal design to thwart a wire going through it?
Even though i couldn't get a wire through it, i'm back and running beautifully.

thanks again.
2008 LX 50
Joined: 16 Oct 2016
Posts: 1
Location: Kamloops, BC
Sun Oct 16, 2016 6:33 pm quote
Vespa LX carburetor jets cleaned
Great, just what i was looking for. Thanks
Vespa 150
Joined: 05 Apr 2017
Posts: 1
Location: Bermuda
Wed Apr 05, 2017 5:00 pm quote
Vespa LX Carburetor Jets Cleaned
Thanks, I followed the instructions exactly as pictured, it took about an hour although 1/2 of that was going the auto supply store to buy the cleaner.

Thanks very much, this was really, really helpful and easy to do by following your instructions.
Joined: 18 Apr 2017
Posts: 1
Location: Washington, DC
Tue Apr 18, 2017 12:42 pm quote
I just wanted to add my thanks - I was intimidated a little but followed the photos/directions and it worked great. After using the carb cleaner on the jet a bunch of times I still couldn't see any light and I didn't have an air compressor but I blew through the jet and it cleared up.
Joined: 03 Sep 2017
Posts: 42
Location: Manchester
Tue Sep 12, 2017 9:09 am quote
Thanks for this, followed on my lx125 and it's made a nice difference, particularly to the idle. I did strip 2 of the screws and needed to mole grip them out, they went back in fine but I will replace them if I can find the right parts next time I do the job.

My idle screw seemed to need a slight tweak after but it runs great now. Tomorrow i'll be adjusting the valve clearances!
Joined: 30 Jul 2017
Posts: 6
Location: Pennsylvania, USA
Fri Sep 22, 2017 12:25 pm quote
Carb Jet Variations
Great post. TYVM!

Going to give my 2009 S50 a cleaning over the weekend. While doing my research about the process, I have noticed there are different carb jet sizes. (i.e. Sizes: 72, 75, 78, 80, 85, 90, 95, 100, 105 & 110) Does it make sense to change to a different size for basic performance issues while I'm in there or simply clean original jet and leave it be? (They are fairly inexpensive.) If so, what size would you recommend? Thanks for advice!
2010 S50 Modified
Joined: 18 Feb 2017
Posts: 53
Location: Deepinnaharta, Texas
Sun Oct 08, 2017 2:31 pm quote

Jet size is matched to engine demand. You cannot gain performance by swapping in a different size jet unless the original jet was the wrong size, or if you make airbox, displacement or exhaust changes.

Cleaning jets is easy enough, and they don't really "wear out" but if it's too messy or too much trouble you can simply replace it with another of the same size.
LX 50 2t
Joined: 08 Sep 2015
Posts: 65
Location: Sheffield
Wed Jan 03, 2018 2:20 am quote
Here's a vid of me cleaning and rejetting my LX 50 2t carb
Not sure if this is of any use (and sorry about the audio), but this is me cleaning and rejetting my two stroke Vespa carburettor.
GTS 250ie Super, Italjet Velocifero, Scarabeo 150, S50,ET2
Joined: 22 Nov 2016
Posts: 288
Location: Winston-Salem, NC
Mon Feb 19, 2018 12:14 pm quote
For those of you stripping screws here is a piece of information. The screws on the Keihin carbs are Japanese and have a slightly different screw. Either get a set of JIS screw drivers from Amazon or file the tip down on your regular Phillips head and youíll have no problems with your carb screws or brake reservoir covers.
Joined: 06 Sep 2018
Posts: 129

Sun Nov 11, 2018 10:30 am quote
Content deleted by tenders. A forum where management/moderators repeatedly quash and delete well-intentioned, constructive concerns about governance issues raised by multiple users does not deserve my participation.
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