Modern Vespa

Greetings:

The pics show my open 2003 ET4 carb, bottomless. I don't recognize the float valve hardware, and have read that the early ETs had Walbro(?) carbs.

The stock ET4 pilot is a #34, and is different from any jet in my collection- Keihin. Polini, OKO, Mikuni - shorter although similar to the PWK and CV jets from Keihin and clones. Wise Greasy125 suggested I need a 38.

Since the much longer #38 I had did physically fit, and the "business end" dimensions were very similar, I decided to try it out. Turns out it works considerably better than the stock 34 - smoother idle, not as many turns out on the mixture screw, less of a flat-spot on initial throttle application.

Still, I'd like to find the CORRECT #38 if possible. I'd appreciate any info on sources.

Thanks in advance for any advice.

Greetings:

Pulled out the Manual! I generally skip the front part but carb is described in section 3-7 as a Walbro WVF6 24mm. It seems 3 or 3.5 turns out from seated is normal for the idle fuel mixture adjustment screw. I'm now wondering if it's worth increasing the main as well as the Pilot from 82 to 84, or at least raising the needle in the clip?

BTW, the carb and bowl were both remarkably clean! , considering this 17 year old scooter had only 500-something miles when purchased last April.

If the one you have works why replace it. If you start having idle problems then go searching. But I decided to check my fall back company Jets R Us and found a listing for Walbro jets. I clicked it and found that it went to their Keihin jets. They do look close. Note that they have genuine jets and the after market may be where your difference is. Look for yourself https://www.jetsrus.com/a_jets_by_carburetor_type/a_jet_kits_walbro_selection.html You can also go here to identify my jet where they have dimensions: https://www.jetsrus.com/FAQs/FAQ_identify_that_jet.htm#KEIHIN scroll down to keihin.

Greetings:

I really appreciate the links, Pink.
The reason I'd like to try the Genuine Walbro Article is that the scooter does not start and run quite as perfectly as it did pre-Malossi. Idle can get erratic, and a bit upredictably so. I can't seem to find a good setting for the idle mixture screw that satisfies cold on-enrichener idle and warm engine idle. There's a trail of chuffing backfires off throttle still. Also the PWK jet installed, but only got 2 or 3 turns on the jet before it bottomed out. I could live with it as it is, but would like to see if the Walbro jet corrects some of this.

Greetings:

I spent an hour fiddling with the idle mixture screw, landing somewhere between 4 turns out and outright removal as the ideal setting. Now someone please correct me if I am mistaken, but a well-respected Member stated that "out is rich". Completely opposite the Keihin PA, PWK, POLINI, etc. Non-CV carbs with which I'm more familiar.

Well if so, even the 38 is too small if it needs that many turns out. Plus it carb-farts and slows down with a sudden throttle blip, another tell-tale of too lean. I ordered the correct shorter 38 plus a 40 and a 42 from Pinkscooter 's link. Thanks again for that Pink.

Maybe of some use to you. I had carb issues on a ET4 recently. Eventually cured it with a new plug. Mine was giving me jip going up hills went through carb no difference. Had been meaning to change plug as no idea how long in there before I got it. Garage only had one of those iridium jobbies so I slapped that in and Bob's your uncle no problem since.

Greetings:

Yes thanks, I installed the same Iridium plug yesterday. Sutures from squeezing my hands into the tight space are healing nicely. Anyway this 2003 ET4 has only 855 miles, and the old Champion plug was doing fine. Still like the idea of the Iridium, although there's no clear evidence of performance improvement.

Have you met my Uncle Bob?!

Greetings:

Jets R Us had the shorter Keihin "equivalent look-alike jets. Listing was SKu K36 SHORT. I purchased a 38, 40 and 42 sizes. Screwed in the 40 because even with the Keihin Long 38, I needed to turn the Idle Mixture Screw out a whopping 4.5 turns out to get a smooth idle. I tried the 40 first. Starts and runs beautifully with the screw now a reasonable 2.75 turns out. I'll have a few spare 38s if anyone wants one.

Now need to find the round Main jets, 6mm head diameter and 9mm length. Looking to get an 84 and 86.

I doubt jet length in this case is important. I see only one difference: longer jet is easier to remove. But what i have experienced with these longer jets is that they are not accurate. #42 jet behaves like #35 and #40 behaves like #38. Please note my jet kit came from china, but i think big part of these jets are coming from there...
What i have eventually did is slightly and carefully enlarged stock short jet till i got desired idle screw adjustment.

Greetings:

And sincere thanks for sharing your experience. I agree, clone jets usually do not behave like originals. Trouble is i was unable to source Genuine Walbro components. WVF Carb evidently came in a dozen variations, unable to locate what model this one is on the casting.

Length of the Keihin did make it easy to remove; it sticks out. That makes me think float level will not be perfect and idle wasn't steady. Better with the 40 clone.

Where to source fine drills? My smallest #65 measures 0.88mm. Too big for Pilot hole - even the #42 jet.

I've had a look at a couple of carbs for sale. On one side it says "Walbro WVF Japan." On the opposite side under the black plastic lever it says 6B or 7C.1 or 7A7.

Greetings:

Thanks very much for the location of the carb model DB! I'll have a look next time I can.

Float level will not be affected by jet length.
You can use sewing needle to enlarge jet, just grind it to be bit smaller than jet and use it as file.
Some jets are measured in mm, so #42 would be 0.42mm, thus making it possible to grind needle to 0.42 mm and use it as drill. But some jets are in some_volume_units/time. This depends on manufacturer and i don't know which numbering option Keihin and Walbro uses.

Greetings:

After several weeks of decent cold-start performance, ISO has begun to misbehave. Cracking open the throttle before the engine is thoroughly warmed results in a stumble, and having to "fan" the throttle go get the engine to rev and go. This is with an aftermarket Keihin SHORT 40 pilot and the stock 82 Main in situ. It seems the "handoff" between running off the pilot and main is compromised, at least until the enrichener circuit is fully closed. Once fully warmed, it Rips.

The problem would appear to have 2 possible causes; 1. The Pilot circuit is getting clogged or 2. The accelerator pump.
Either way I'm looking at dismantling and cleaning, a process I have previously done with other CV carbs, but hesitating because if the diaphragm rips or some other snag occurs, I'd be without motorway-capable Scootage.

The other alternative is outright carb replacement. A Keihin would have more easily obtained jet options. I saw that ScooterPartsCo has a genuine 2006-later Keihin replacement for the Walbro, for around $230. If anyone has experience with this (or perhaps a less pricey equivalent?), I'd be grateful.

Hi,

I have bought this one from ebay and i am happy with it. Seller is reliable, have bought number of parts from him. You can check if he has got what you need and if he can ship it to you.

https://www.ebay.co.uk/itm/CM156010-Carburator-Keihin-Piaggio-Genuine-Piaggio-FLY-125-LBMM57100-2006-On/263375482699?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

Greetings:

Sincere thanks Isdeekelis! I have had some issues in the past ordering from overseas, and I will use the information to see if I can locate a North American source.

I have ordered many parts from this seller from Greece over the last few years with no problem always emails to say what's going on and when posted. No problems with him over covid lockdown.

Greetings:

Misbehavior continues. From Idle, giving throttle causes revs to rise a little, then drop abruptly, almost stalling. In fact today it did stall once. "Fanning" the throttle occasionally brings up the power, but it remains balky. The behavior is inconsistent, however. It works fine most of the time.

Believing this 17 year-old Walbro to have possible internal problems probably resin in the slow circuit, I broke down and ordered an LX 150 Keihin replacement from Scooter PartsCo for about the same price as the Greek vendor you so kindly provided. The Keihin jets are easier to procure and the diaphragm won't be 17 years brittle. I'll report performance improvement, if any, when installed.

The Walbro I will dismantle and evaluate and clean thoroughly once the Keihin is on and working.

Greetings:

From ScooterPartsCo arrived this today: Will install the standard Keihin 38 jet and perhaps a larger-than-82 main to see if the "handoff" issue at midrange is corrected. Fuel and vacuum lines to be replaced and petcock filter inspected as well.

Greetings:

Replaced the fuel, vac, and evap lines from the carb. Discovered my vacuum-operated fuel valve doesn't stop fuel flow unless you Blow into vacuum line. The Filter Screen looked fine - no sludge or resin. Anyway I'm ordering a new one today. The line from the float vent was cracked at the carb AND at the "T" junction of the Evap system. Replaced that too. The "Handoff Hiccup" still happens while the engine is cold, but clears up when warm, throttle response is now linear. Jets are 38/82.5 from Jets R Us. Power is Awesome, but Tropical Storm Beta is 30 miles up the road and will postpone final testing.

Greetings:

Streets in Deepinaharta dried up for exactly 15 minutes, permitting a ride around the block. Hot Dang!! Keihin rocks. Can't get to top speed for a few days but will post outcome.

That mid range hiccup may be solved by raising the needle a little. I don't know if these have notched needles with clips. If they don't I've slipped small washer on the needle then slipped it in the hole to rase the needle. It helps that mid range when it's cold.

Greetings:

Thanks PS! Did a bit of Inspectin' tonight. More to come. Sticky slide seems most likely issue. [EDIT] This documents dismantling of the weirdo Walbro 2003 carb that came with the ET4 of this era. The Keihin is on the scooter and working well.

Isn't this a brand new carb? I'm confused why the slide would not be smooth and the needle gritty?

Greetings:

Sorry this is the surprisingly clean 2003 Walbro. More to come.

Greetings:

So here's the rest of the story of the Walbro inspection;
The pilot jet (a 40?) was brand new, and of course quite clean.
The 82 main was likewise in good shape.
The bowl was surprisingly clean. I suspect someone went through this carb before my April purchase, at 541 miles. Perhaps to get it running?
The Bystarter was working fine, although it closed pretty quickly after startup, with the engine not Quite ready to run off the pilot and main alone.
The Float Chamber was a real mystery. Some weird brown dust - like powdered cinnamon? - was contained 'neath the dome. Brushed it out. Float stickiness might be explained by this stuff.

Greetings:

In the course of replacing carb and lines, I discovered my vacuum-operated fuel valve wasn't functioning correctly. I fuel flow wasn't completely blocked without vacuum on the smaller line. Evidently both the Walbro carb and the new Keihin have good functioning float valves, or there'd be a lake in my garage. Also now I know exactly how much fuel is in the tank when the Low Fuel light starts to flicker.

So, I recently purchased a 2003 Vespa et4 150, 9nly 651 original miles. Kept bogging down on me. Upon inspection after breaki.g down the carb, i.also ran across the brown cinnamon sugar. I found out what it is. It's the gasoline 9ver flowing into the filter box, eating away the air filter, and the pressure from the motor sucking it back up into the carb. Yeah, quite fun. Also, I went from a .38 to a .40 jet (if I remember correctly), and the difference made this little scooter came to life. Also, I called the scooter store to have a battery put in my clock in the dash. Wanted almost $300 for a 4 hour job. I did it in less than an hour (with zero experience) and cost me $11 dollars. Yeah buddy. Good luck to you all. Thanks for accepting me in to the group.
Joshua C.

My two cents worth from recent modifications:
Buy a Chinese copy of CVK carburetor on Amazon labeled "JFG Racing CVK". It is SAID to have a 30mm ID intake throat, but its actually 28mm, which is what you really want and it will fit in your rubber intake manifold.
Discard 117 main jet for 140-150, (the needle and idle jet are fine as is) depending on additional intake/exhaust mods, which I recommend to be:
Siti exhaust.
Discard ALL restrictive intake and filter hardware and replace with 2" O.D. 3" long rubber connector to 1 7/8" O>D>PVC pipe 4" long followed by appropriate rubber plumbing connectors and finally a K&N filter. Support the intake pipe and filter with one of those less flexible all black rubber "bungie "cords 15" long between the rubber holes and hooked at each end in frame holes on each side of the helmet bucket opening. This will keep the intake apparatus from banging down on the flimsy plastic mud guard over the rear wheel and hitting the rear tire and wearing a hole in the mud guard .
This carburetor is a bit taller than stock but it WILL fit with some finessing and possibly a little grinding of the underlying casing. I slipped a sheet of heat shield under the carb to protect it from vapor lock. Also, the stock two way throttle cable mechanism will have to be modified to accept the single cable ET4 throttle cable.
Its worth the trouble. Power increase is substantial, enabling you to MAINTAIN 50-55 up most hills instead of falling off to 45 and holding up following traffic.
And its cheap...

The powder in the carb looks like crumbling foam air filter. I had an et4 with issues.. i also have an Aprilia mojito with the same engine. The Aprilia was older, low mileage and filter was crumbling into carb...

Morning all

I've got a very old beater 2002 Piaggio/Vespa ET4 125cc

It's been sat outside as spares or repairs for a long time now. In my search for a replacement float for the Waldro carb I've found this post - it's the same as in your photo wheelman.

Before I start with a replacement carb I was wondering if anyone knew about spares for sale from the UK - or if spares are available at all for a very old carb!

I may have a spare will check when get chance tonight and let you know.
Spares are hard to come by only second hand on eBay stuff.

Well that's great of you for even thinking about it. Appreciated.

Yes there are a few used on eBay but wondering if I'd be in the same place.

Missing a few other bits like float spring and pin to hold the float in place. It hit the floor and promptly vanished.

Have recently bought a copy carb for a petrol jet washer that cost £30 and works great.

Has anyone else changed an OEM carb for copy type?

Greetings:

I ended up buying a Keihin replacement from ScolterWest for around $225. Sold the Walbro once I was sure the Keihin solved all my issues , sorry.

Sorry had a look but can't find one.