Modern Vespa

Hi guys. Hope you're all having a great Christmas! so, due to very few days off recently, I thought I'd use today to tackle my Vespa et2-50cc that's been stood lifeless for a month. I bought it as a fixer upper earlier this year, fixed her up, new paint job, the lot! Had a great spring/summer with it,but slowly it became harder to start, until it just stopped. By the way, I had no prior knowledge of scooters or mechanics, so when I bought the project, I pretty much fixed it up by searching on modernvespa,trial and error, and hard work/luck! (It was a proud moment when the once scratched up, hand painted light blue, non running scooter emerged from the garage, now Matt black with red trims, de restricted, and running perfectly for its first rude out!). Anyway, a new air filter, cleaned out exhaust, new fuel tap and spark plug sorted the starting problem straight away. It started first time everytime. But the problem slowly came back again until it wouldn't start at all again. Today was the first chance I had, so I removed, dismantled the carb, cleaned the jets (I think one was blocked), checked it all over, and fitted it again, but it made no difference and still wouldn't start. I have new fuel, a good spark, clean carb/jets, and no visible problems. I'm wondering now if the new fuel tap is faulty, and has slowly got worse, hence the original problem creeping back? One thing I also noticed, was that the kick start would only ever work when the scooter had already been started (with brute force that almost drained the battery each time, if that sounds familiar to anyone?
I have more time to look at it tomorrow, so any help or ideas would be very appreciated. Thanks for your time.

If you have a good spark and good compression the problem is probably lack of fuel supply possibly due to a faulty fuel tap....


To get it started.....

You can put a small amount of petrol directly into the spark plug hole.....


If you think it is a fuel tap problem try one of the following....

1)Suck on the vacuum tube to get the fuel tap to open up until you fill the fuel bowl to the top

2)Use a pipette or small funnel.... remove the fuel line and put fuel directly into the carb via the fuel line hole

3)Remove the float bowl from the carb and fill it with petrol before you fix it back on again (needs a steady hand to keep it level)

4)Use some spray "Easy Start" directly into the air box (spray the air filter)


All of these should get enough "fuel" into the carb to allow the scoot to start and then hopefully the vacuum/vacuum pipe should do the rest.

Also check the condition of your vacuum pipe. If its compromised it will not create enough vacuum to open the tap.

Hope this helps

Fabio

Another 2 things to review are...

1) the settings on the air/fuel mixture screw (should be approx 2.5 turns out from fully closed)

and

2) test the autochoke - if you need help with how to do this then just shout up

Thanks so much Fabio. I did hear on modernvespa that you were a bit of an ET legend! I will try your suggestions today and report back!

After you've messed a bit.....

If the automatic choke is problem free, the starter cranks the engine sufficiently, there's fuel at the carb and there's a strong spark then there may be an engine problem and you need to check the cylinder compression. To do this accurately you will need a compression tester. It screws in instead of the spark plug and measures cylinder pressure. When you crank the engine you should see a reading of approaching 125-150 psi. If it's 100 psi or less then its likely that you have an engine problem (probably failed piston rings) and you will need to remove the cylinder head to gain access to the piston rings. A trick to try if you haven't got a Compression Tester is to hold your finger tightly over the spark plug hole with the spark plug removed to see if your finger is forced away strongly when you try to turn the engine over - it may just indicate that there is very little compression if the force is very minor. Another tip is to add a teaspoon of engine oil through the spark plug hole and try to crank the engine again. If you then get a better compression its likely that the piston rings are shot, as the oil you added sealed the rings for a short period of time and hence temporarily gave you better compression.


This is an excerpt form an article I wrote for the MV Wiki..... here's the full notes.....

Getting Your 2-Stroke to Run Properly


.

Hi again! I posted earlier but it vanished! Well, after your suggestion and info Fabio, I filled the carb/bowl with fuel via the vacuum hose,(can't believe I overlook that!) and it started first time!!! Really pleased as it's been 3 MONTHS since I used it! Rode it all day with no problems, and it's been running as good as it ever has.
Just went out to cover it up for the night, put the keys in just to check, and it wouldn't start. :-/
I'm not gonna get too discouraged though, as I may have just flooded it. I'm so used to fully opening the throttle to start it I might have done it out of habit, as I could smell fuel. I'll try again tomorrow, but if it's a familiar problem to anyone and there might possibly be a reason, then any suggestions would be very welcomed! Kneill.

Fuel tap is tatered...or float in carb bowl is not closing properly ....

Thanks again Fabio. It started first time again this morning, but I'm not gonna play a lottery on wether it's gonna start or not every day, so will address both things you mentioned. I will admit that I randomly ordered a fuel tap online, and did notice that I was replacing a metal tap with an all plastic one. Would there be a preference? Also as it was my first time on a carburettor, which I have very little knowledge of, I did check the float pin was straight, and the float moved freely, but how would I know if it wasn't operating properly?
I was surprised at the lack of information about the float needle. It dropped out when I undid the carb, and I had to zoom in to a terrible pixilated photo online to see where it originally went! The Haynes manual barely mentioned it, but someone online mentioned ' when the float is upward, the needle sits inside the body of the carb'. So common sense told me it kinda hooked into a space in the float, and goes up into a channel when the float and pin are replaced. Hope that's right? (I'm guessing is was as I rode all day!). I really hope all of my questions aren't getting annoying! But after a lot of promises/letdowns, a hugely frustrating couple of months without the scooter or the knowledge to fix it (so I thought anyway! Honestly, I decided to try and tackle it myself because of a 'right! If no one else can be bothered to help me out, I'll do it myself!' attitude, I am very eager to learn, and eventually hope to do any repairs or work myself. It's part of scootering right?

you could say that...if anyone is going to ET2 heaven. Its the Fabster!

The float needle(Marked as D in the photo... I think this is what you're referring to) sits in a hole (Marked A), the needle is used "point upwards" and at the bottom of the needle it clips into the recess on the circular float (Marked E) prior to putting the float hinge in place.

I found this photo on the internet.... it may not be identical to yours but should be close enough for you to get the gist......



You should ensure that the needle "seats" well and that the float moves freely before replacing the bowl (Marked F).

Prior to finally replacing the bowl you can use the float to test if the needle is closing off the fuel supply by lifting/lowering the float, with the float down it should flow fuel, with the float up it should stop the fuel.

The fuel tap you require should look like this....

Man, this is such a great forum! I'm a member of one other forum (non scooter related!) and all they do is disagree and argue!
I did replace the float needle correctly by the looks of it,and instinctively checked it was all moving freely. But I'm sure a second look won't hurt?!
The fuel tap I fitted recently (and may have doubts about) was the same shape and fittings as the one you kindly posted here, but it was all plastic as I remember. I'll check that out also, and will replace it with a metal bodied type anyway. I have a couple of days off work next week, and have put them aside to explore the ET, and replace anything may be causing a problem, or even has the potential to be a problem in the future. As I mentioned, it's been out of action for 3 months, so I need to be able to trust it again, if you know what I mean!?
As soon as I'm as sure as I can be of it's reliability, I can begin my plans to customise the hell out if it. I only did it a year ago (it's matte black with red spiral graphics-taken from the horror movie SAW, but they're pretty subtle.not really into 'themed' scooters). But I'm thinking something different for 2014.

If Carling did Forums...