Vespa ET2 Carb problems - No power, now too much power
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Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Sun Jun 19, 2011 8:02 am quote
I've just bought my first scooter, and it has something wrong with the carb. The bike would run for about a minute or two max then slowly cut out.

So I opened it up today and removed the carb and found the pipe on the bottom where I think the air comes out was full of black stuff (it's the thin pipe that's about the same size as the oil pipe.

I sprayed carb cleaner into it and all the other pipes to clear them all out and put it back in.

Now when I start the engine it's like I've got the gas on full when I'm not even touching the gas at all...

Can anyone help? Sorry I'm a complete beginner with all this.

It's a Vespa ET2 50cc 2003. I think I may not have connected the big, wide air thing that is connected to the air filter properly. Also no oil came out of the oil input pipe, is that normal?
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2007 Vespa GT200
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Sun Jun 19, 2011 8:47 am quote
Carb Spray, now too much gas/power?
Being as you started with no/low power and now too much, I would say either the carb spray cleaned the carb, but the float/needle tip is sticking a bit or you did not connect hoses properly and you have a vacuum leak.

Before starting any "venture" where you start disconnecting/disassembling always take digital pictures before hand, label everything with masking tape and marker pen even so far as laying the screws out on the floor in the exact pattern (or punch holes in cardboard pattern and tape 'em in).

Look in the Wiki tab for your model scoot for the service manual...MV posters and sponsors have been kind enough to make things easy for us newbies (me included)...be patient and methodical...don't beat yourself up too much, common sense is used too often and a misnomer...as it is a "learned experience."
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Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Sun Jun 19, 2011 9:32 am quote
Thanks for the reply. I'm back to square one now as it's running but cuts out a couple of minutes later

I'll have a look online tonight but might take it to the garage for this one.
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Sun Jun 19, 2011 9:43 am quote
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If the scooter is stalling at idle, and its been stood around for a while unused, there may be a build up of fuel deposits in the carb.... it may be an easy fix as you can perhaps get away with cleaning out the idle jet. The idle jet only supplies fuel at idle and if its hard to keep it ticking over without revving the scooter then I'd start there. Its an easy fix and I can talk you through it, it will take you perhaps 30mins to do this.

Fabio

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Member
Vespa ET2 50
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Posts: 22
Location: London
Sun Jun 19, 2011 10:08 am quote
Thank you! It's not just cutting out when it's idle though, it always cuts out when it's moving. It's almost like fuel isn't getting to the engine fast enough. The longer I leave it without running the further I can go before it cuts out.
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Sun Jun 19, 2011 11:01 am quote
svb123 wrote:
Thank you! It's not just cutting out when it's idle though, it always cuts out when it's moving. It's almost like fuel isn't getting to the engine fast enough. The longer I leave it without running the further I can go before it cuts out.
.

Ok....

Take look at these and see if they help.... Getting Your 2-Stroke to Run Properly

2-Stroke Carburetor Set-up Technique

I'm thinking that its got to be either fuel supply or insufficient spark.

Have you checked the spark plug to see how it looks?

Fabio

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Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Sun Jun 19, 2011 11:08 am quote
Thanks Fabio, I'll take a look.

Spark plus were changed yesterday, didn't really make a difference but I know it's not them as it has new ones now.
Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Sun Jun 19, 2011 11:19 am quote
Ok, what I did today was remove the carb and spray carb cleaner into all the tubes that feed into the carb. I also sprayed the outside of the carb and the big holes but may have missed the tiny holes on the actual carb.
Member
Vespa ET2 50
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Posts: 22
Location: London
Sun Jun 19, 2011 11:46 am quote
These are really useful, thanks! I'm going to try the idle mixture screw first.
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Sun Jun 19, 2011 12:33 pm quote
.

I think it will be the idle jet that's blocked.

A very common problem is blocked jets in the carburetor. The jets have tiny holes in them that the fuel passes through to supply the carb and these become gummed up with fuel residue. You will find three jets in the carb (Main jet-used for Wide Open Throttle, Idle Jet-feeds the carb at idle/low revs, Choke/Power Jet-gives extra-rich fuel supply when starting from cold) and its easy to remove the jets and clean them out with a spot of Carb Cleaning Fluid and/or with compressed air. A tip is to blow through the jets with your mouth and then hold them up to the light to see if you can see clear daylight through the jet's bore. Whatever you do don't be tempted to prod the hole in the jet with a bit of wire or a needle as this will enlarge the jet's bore and be the cause of tuning problems at a later stage.

Hope this helps

Fabio

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Dellorto Carb.jpg

Hooked
1998 ET4
Joined: 24 Apr 2010
Posts: 123
Location: London
Sun Jun 19, 2011 12:43 pm quote
Hi Fabio, does that picture accurately reflect the underside of an ET4 125 carb? What (if any) is the effect of tightening and loosening the jets?
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Mon Jun 20, 2011 1:46 am quote
.

Hi Simon

No, that one is a Dell'orto PHVA used in a lot of ET2s

The ET4 125 is usually a Keihin CVK30 (or similar size), or a Walbro.

The Keihin CVK looks like the picture below (the picture is for a CVK40 but the components in the picture are almost identical to the ET4 ones), and whatever your carb it will give you sufficient information......




Your question... "What (if any) is the effect of tightening and loosening the jets?".... Answer... No effect, just make sure that they are screwed in properly, the only benefit with the jets is to make sure that they are spotlessly clean and not blocked in any way whatsoever. They are adjusted by replacing the jets for larger or smaller bores to allow more or less fuel to flow into the air/fuel mixture making it either richer or leaner.

The only way to properly get an indication of jet size is to run some Plug Chops, I talk about Plug Chops in this Wiki Article I wrote for the ET2.... but all of the principles apply to your scooter..... 2-Stroke Carburetor Set-up Technique


You may also like the following Wiki Articles that I wrote with exactly this type of learning in mind....

How a Carb Works

Getting Your 2-Stroke to Run Properly

2-Stroke Carburetor Set-up Technique

CVT Principles - How it works, how to improve it....

Hope this helps

Fabio

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Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Mon Jun 20, 2011 2:53 am quote
Fabio does it matter that there is no flat head screw on top of the power jet?
Member
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Scooter Pimp
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Mon Jun 20, 2011 3:11 am quote
.

Hmmmmm, that's interesting!!!

Is the tube threaded for a jet???? either on the inside or the outside???

Also is it a Weber carb or a Dell'orto carb??

Fabio


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Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Mon Jun 20, 2011 3:21 am quote
I'm sorry I don't know how to find these things out!

Also, the plastic cover that sits exactly on top of the image you posted, covering all three jets has a black rubber pipe poking out that was plugged into nothing. Should it be plugged into something?
Member
Vespa ET2 50
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Mon Jun 20, 2011 3:21 am quote
It's not threaded for a jet as far as I can see and it seems to fit perfectly into the plastic tube on the cover
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Mon Jun 20, 2011 3:30 am quote
svb123 wrote:
I'm sorry I don't know how to find these things out!
.

On the side of the carb's body it should be stamped with the Makers name and the type of carb, you will probably have either a Weber 120M or a Dell'orto 17.5 PHVA - the photo you sent looks like a Weber.

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svb123 wrote:
Also, the plastic cover that sits exactly on top of the image you posted, covering all three jets has a black rubber pipe poking out that was plugged into nothing. Should it be plugged into something?
.

The tube you're talking about is probably the drain pipe from the fuel bowl, it shouldn't be attached to anything and only works when you undo the screw next to it on the fuel bowl for when you want to empty it out.

The photo I posted was of the Dell'orto, but the same principle applies

Fabio

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Mon Jun 20, 2011 3:32 am quote
svb123 wrote:
It's not threaded for a jet as far as I can see and it seems to fit perfectly into the plastic tube on the cover
.

I can't remember on my old Weber carb (I think its a weber one that you will have - they were the standard sort on the older ET2's like yours and mine - I replaced mine with a Dell'orto 17.5 PHVA - it feeds the engine better when its a tuned a touch).

I think that I still have it in the garage somewhere at home, when i get back this evening I'll take a look for you and upload some photos.

Edit : In the meantime, describe to me exactly the problem that you're having - go into some detail, how it pulls/doesn't, how it sounds, how it revs, etc so that i can help you diagnose your problems.

Fabio

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Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Mon Jun 20, 2011 3:55 am quote
Thanks Fabio, you're a legend.

I bought the bike Thursday, the guy said a garage in Camden told him it needs a new carb and they'll charge 200 and he's moving out of London and won't need it anyway.

I called Honda Riders in south London before buying it and she said it shouldn't need a new carb, and looking at it I can't see why either, it doesn't look old and the scooter has only done 8,000 miles. I'm not sure the guy knew much about bikes, he said he's never pumped the tyres up at all and they were quite flat.

It was serviced and mot'd in March this year and I did notice the mileage is exactly the same as it was at it's service 3 months ago so I think it's been idle all that time.

The problem it had when I bought it was it cut out after 2 minutes, whether it was idle or moving, but going up hill or going open throttle killed it so it seemed like a lack of fuel issue.

I took it to another garage, they changed the spark plugs as that's all they had time for before they closed but said it's likely the carb jets are blocked (I didn't tell them what the other guy said about a new carb).

I've just sprayed carb cleaner through the jets and can see through the main and idle jets (I couldn't see through the idle jet before).

I put it back together but I think I've done something wrong as now the engine sounds normal but cuts out after two seconds, whether I start to rev or not.

When I put the screws back on the jets I screwed them tightly, then unscrewed them about a turn and a half and matched them up to how the image you showed me is.
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Mon Jun 20, 2011 4:15 am quote
.

When you cleaned the jets out did you completely unblock them???

What I do is to remove the jets (all three/two) and then soak them in carb cleaner or brake cleaner overnight, then in the morning I blow them out to clear the gunk that's been loosened by the carb cleaner, you can either use a bit of compressed air or if you don't have a compressor then I've found that using a bicycle pump to blow out the jets can do the job if you position it carefully.

The jets need to be really clean (the bore through the jets should look clean and perfectly round of shape), look into the sky through them to give yourself a good sight of the bore, but don't be tempted to prod at them with a needle or wire as this will overly enlarge the bore and make the carb erratic.

Fabio

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Member
Vespa ET2 50
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Posts: 22
Location: London
Mon Jun 20, 2011 4:21 am quote
Ah ok, no I just sprayed them a lot.

Can I soak them in carb cleaner mixed with water? I just have this spray can.
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Mon Jun 20, 2011 12:30 pm quote
.

Hi SVB

As promised, I've dug out my ET2's old Weber 120M carb.... here are some photos of it.

My Weber doesn't look exactly like the carb in your link, yours may be a newer/older version, but from what I've seen it looks like it should have a Jet in the tube on the bottom left.

I'm hoping that some other MVer will chip in here to identify your exact carb.

I've got a manual out at the moment and for all of the UK ET2 applications its states a measurement for the bore of the Starter jet so it sounds like yours is missing, hence excess fuel may be getting through and making it run too rich/flooding it.

Anyway... have a look at the photos...they're a bit blurry but I hope that they help you in some way.

Fabio

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12mm Weber.jpg
Weber 120M

Weber Connections2.JPG
Labelled for the connections

Image0472.jpg
From underneath, Choke/Power/Starter Jet is bottom left, Idle jet is the small one more to the centre, Main Jet is the larger one just to the right,I've just noticed that the jet is missing from its position-its marked "Weber" on the black float

Image0474.jpg
When you remove the Choke/Power/Starter jet you'll see that its part of a "stack" with the thread being right at the bottom of the tube that it sits in.... so you may have missed this

Image0479.jpg
A blurry close up of the "stack"

Image0481.jpg
Just above my thumb you'll see its marked "Weber", and higher up in the metal its stamped "120M"

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Mon Jun 20, 2011 12:33 pm quote
.

I'm just looking at your carb again..... it does look more like my Dell'orto to be honest!

I've uploaded it below for you.

Fabio

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Mon Jun 20, 2011 12:40 pm quote
.

This might help too.... have a look at item #6.... Getto Avviamento translates as Starting Jet !!

Member
Vespa ET2 50
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Location: London
Mon Jun 20, 2011 10:09 pm quote
Fabio you are amazing! It is the Dellorto and I can see it's missing part 6! I'll call a garage and order it today.

Will update you when I've fitted it
Member
Vespa ET2 50
Joined: 19 Jun 2011
Posts: 22
Location: London
Mon Jun 20, 2011 11:09 pm quote
So I'm going to need 26 and 27 right? As well as a carb kit for the gaskets and O ring?

http://stevebrewer.eu/wp-content/uploads/2011/06/330332927.352268.jpg

I don't know why images aren't working for me.
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Mon Jun 20, 2011 11:20 pm quote
.

No, I think you just need the Starter Jet "Stack" as in the photo I uploaded of it in the palm of my hand. Its a "one-piece" jobby.

They are about 5 I think, your garage may not have them if its not a vespa/piaggio/scooter dealer - try SIP or Beedspeed or AJ.Suttons etc etc - or even try ebay.

I've never bothered with gasket kits etc, as long as they are removed carefully then they will be able to be re-used.

To upload photos.... FAQ: How do I upload a photo?

Hope this helps

Fabio

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Member
Vespa ET2 50
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Location: London
Fri Jun 24, 2011 2:30 pm quote
Hi Fabio. Just to update you, I caved and took it to a garage.

They replaced the carb with a second hand one and it worked much better but when it reached 40mph after about 3 miles of 30mph or so it cut out.

I took it back and they found brake fluid in with the oil (god knows how that happened).

After draining it and replacing with clean oil, it still had trouble starting.

They checked the compression and it was around 40 psi or something really low. They said new piston rings would probably do it (and I've just confirmed that by reading the section on this in your post), but then they told me they have to drop the engine (not true according to Haynes) and it would take 3-4 hours (not true according to your post!).

So glad I took it away to investigate myself. Have ordered some new piston rings and will be attempting this as soon as they arrive.

Thanks again for your help!
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Sat Jun 25, 2011 12:11 am quote
.

Changing the piston rings can be done with the engine in situ on the ET2 - I know cos I've done it!!

It will take you about an hour or just over to get them replaced.

Fabio

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Member
Vespa ET2 50
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Sat Jun 25, 2011 1:11 am quote
Will I need anything besides the rings? Haynes says I need to replace the cylinder gasket and piston circlips with new ones...? I'm not sure they come with the rings I ordered
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Sat Jun 25, 2011 1:16 am quote
svb123 wrote:
Will I need anything besides the rings? Haynes says I need to replace the cylinder gasket and piston circlips with new ones...? I'm not sure they come with the rings I ordered
.

Gaskets yes, circlips you'll probably be ok...but if youre going to order the gasket then the circlips will only be a few more pence.

Fabio

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