Modern Vespa

So I have a novice question. I am trying to avoid taking my ET4 into the shop but i am certain it needs to have a carb readjustment, is there anything I can do myself without having an advanced knowledge of walbros?

thanks,

MIKE

Well, an adjustment does not require dismantling. You'd only need to dismantle to replace or clean jets, etc. The trick is, if you've never adjusted a carb, you might not get any closer to the desired result. Also, you'll need a special tool to turn the adjustment screw.

What makes you think it needs an adjustment? How is the bike behaving?

Not sure about the 2005, but my 2004 ET4 does not require a special tool to adjust the air/fuel mixture. Just a standard screwdriver. If you are standing behind the scooter, it is on the lower left-hand side of the carb, lower than the evap hose connector. I think there are some pictures for an LX adjustment.

If you need to clean the jets, I've found that loosening the two clamps holding it in place, detaching the wires, and then flipping it around so the bowl is on top works best. Then unscrew the four brass screws to get to the jets. Again, I think there are some pictures for changing the LX idle jet which are mostly applicable.

I've found that after cleaning and re-oiling the air filter, I've needed to readjust the air/oil mixture. The system seems very sensitive to changes.

Shane

You don't must adjust a carburetor, without a real need.
However you do not need to disassemble the carburetor to adjust the idle, minimum, maximum, etc.
Get the your carburetor layout and looking for the Idle screw, minium screw and Air/Fuel - Maximum screw.
Adjust only if you are lean or very rich. With the screw driver only 1/16 of turn never turn much the screw. It's not a game.
In general in carburetor:
counter-clockwise ---> rich
clockwise ---> lean

I just had the carb rebuilt, but lately my scoot feels like i am flooding the engine I am hard off the line (if I am really careful, it will run fine),but it ALWAYS boggs down or feels flooded when i am running about 20mph until about 40mph. I was thinking it could be a mid range jet? I've checked the fuel lines, all the junctions are tight. It idles perfect and starts clean (because of the two cycles of seafoam i ran through it).

What do you think? I'm worried about doing it myself because I do not want to make the problem worse.

So would you say it is relatively simple? The adjusting?

Very, very simple. Just let it warm up and then turn the a/o screw in and listen to the engine.

Shane

My scooter idles fine, the problem doesn't really happen until i've hit about 20 mph, so what would i listen for in the engine? (if that makes sense)

thanks again

I'm not a mechanic, but here goes... As you move the screw in and out, you'll start to hear the engine reach it's peak. I would probably find the peak and then turn it just a touch more counter clockwise, so that it is a little bit rich. Take it for a spin and see how it runs. It is easy to readjust and try again.

Shane

If your idle seems fine, but you believe the mixture is off, then your idle is probably set too high. You can't properly set the idle until the fuel mixture is set up properly. As far as messing anything up, turning the screw to its original position will restore the previous mix.

thanks everyone for all the help. i'm going to do some tweakin' later on tonite. i'm going to get looking for a carb diagram, i think its a walbro wvf6.

Based on my own experience, you might find that the bog is actually a lean surge and you need to turn the mixture screw out. I would also check the air filter and make sure it is well oiled. I think the manual suggests a mixture of 50/50 Oil/Gas and then let the gas evaporate.

Again, I'm no mechanic...
Shane

Based on the OP's description of the problem, it sounds more like a mid-range mixture problem to me -- possibly related to the needle/needle jet -- than an idle A/F mixture problem. Maybe a needle clip adjustment is in order to adjust the mid-range mixture.

Check this out:

If your engine not spin well to 20 KM/h or about +/- you have to set low-mid range screw on the carburator. Usually it is located in the point in the figure. The layout of the carb is LX 125 4 stroke but it should help to search on your wallbro. When you have found it, if your vespa is rich turn 1/16 clockwise, open the throttle to max and try with test on road. Small pass on the screw. Do not overdo this else your vespa will be lean to low to mid range.

You can definitely check the position of the needle, mine is at the lowest setting, but that is a little more difficult, and adjusting the mixture screw might do the trick. Awesome chart, BTW.

Shane

I beleive let a pro do what a pro does. It will save time and money. If

anything goes wrong then the pro will fix or replace. just MHO

Paul

I respect your opinion, but it all depends on one's own abilities and one's confidence in them. Without doing, there is not much learning.

I love not being dependent on the pros... who may or may not be more competent than I am.

I completely agree and it can get very expensive testing things out at $90 per hour.

After all of the cabs I have rebuilt (mostly keihins from Hondas) I have really come to appreciate fuel injection on my 250gts.

i adjusted the fuel air mixture screw and it really didn't solve the problem. i checked the spark plug and it seems burnt. may be a case of fuel foul. i'm going to the dealer to get a spark plug today, i'll change it and see what happens.