Modern Vespa

I bought a 2009 Vespa S50 a couple of years ago. It was cheap and not a looker (paint work had been redone poorly so I assumed that it's seen some action). It moved, had 22k on the clock and wasn't perfect e.g it would have restart problems if the engine was already warm e.g. after a fuel refill or it would cut out at very top speed sometimes.

Anyway, as with most of the UK, we entered lockdown in March 2020 and the scooter has been stored away for 1.5 years and unused until this month.

Being a complete noob, I just kept it in the garage which I've since read can lead to problems.

Now I find that although the engine turns over, it never starts up.

Thing's I've already tried are:

1. I replaced the battery with a brand new one.
2. I took off the carburettor and cleaned the jets with carb cleaner (to be honest, they didn't seem blocked but I read that the cold winter storage may have gummed them up).
3. I replaced the spark plug with a brand new one.
4. I drained the petrol from the tank with a syphon and replaced with fresh petrol (I emptied the old stuff again that I had refilled in the carburettor in step 2 too...).
5. The kill switch from what I can tell is off (to be honest, it doesn't move at all)

If you are interested, I can take a short video of me trying to start it up for you to listen to.

Anyone with suggestions on what I can try next?

I'm tempted to take it to a pro mechanic now but I'm also half tempted to bin it and get a new scooter. I've enjoyed learning about the mechanics about the scooter but now I just want to ride again. Thanks for any comments.

Did you charge your new battery? Most new batteries need to be charged prior to installation to get full charge.

It looks like you have a pretty bad kink in one of the hoses.

Also you could have a crack in the vacuum line that goes to the fuel tap.
Does the carb bowl get filled?

>Did you charge your new battery? Most new batteries need to be charged prior to installation to get full charge. <- No, I didn't but I did put a voltmeter across it and the reading was as expected. This was the one that I purchases and it does say that it's 'pre-filled and ready to use': https://www.tayna.co.uk/motorcycle-batteries/yuasa/yb9-b/

It looks like you have a pretty bad kink in one of the hoses. <- Agreed, this I believe is fuel line. Going to try and replace the hose. Will pick up something from Amazon.

Also you could have a crack in the vacuum line that goes to the fuel tap. <- So, I've seen two hoses from the fuel tank that end up going into the carburettor. One (the one with the kink) delivers fuel and the other must be the vacuum line. The latter has a short hose from the fuel tap that feeds into something (called the petcock I believe) and then another hose is attached on the other end that goes into the carburettor. I've not check for any crack but I will do now (thanks). From what I recall, the vacuum hose seemed Ok (but it is a darker colour so I may have overlooked something).

Does the carb bowl get filled? <- Yes

You need to confirm the presence of spark - especially since the kill switch is acting suspiciously. Pull the plug from the engine, touch the base to the engine (ie to ground) with the plug wire still attached, and crank the engine. You should see a nice blue spark jumping the spark plug gap. No spark = no start. Could be the kill switch is in “kill” mode, or the CDI module is bad, or the plug wire is bad, etc.

Just an observation: I'm surprised there is that much sparkplug showing in your picture. A lot of gunk could get down in there and then when you replace the plug it could fall into the cylinder! There is a larger more protective rubber boot on my LX that helps keep it clean.

#1 kill switch
#2 that kinked up fuel line there.

after that, verify fuel flow and check for spark and check your compression. if you haven't you'll probably need an air filter.

The kinked line on the right side of carb is the vacuum line that allows the petcock to open and flow fuel to the carb via the dark line on the left side. If it's kinked you might not be allowing fuel to flow to carb so get that fixed first.

Also check that petcock is in fact working. You can create a vacuum on it by sucking on that clear line gently and see if fuel flows out the dark line.

I have the same engine/carb on my Typhoon and am in the process of replacing my petcock now.

"Won't start" diagnosis for beginners

IMO the first and easiest thing to confirm is that you have spark.

Thanks for all the comments so far.

So I can confirm that a spark appears when I start but not always.

When I press the start button, I sometimes hear the engine turning over (and I will see a spark) and sometimes it's just a whining sound (where I don't get a spark). You should be able to hear it in this video that I made:

My guess is that there are two problems that needs investigating a) there is no spark and I just hear the whining sound b) the engine turns over, a spark is produced but it still doesn't start (I'm hoping that this may get resolved by changing the fuel and vacuum lines later this week).

Any ideas on a) or b)? Is there a way to test the CDI? Thanks.

Interesting...

So, the engine turning over is what generates the spark. With that in mind, the fact that you get spark when it turns over suggests your CDI and spark-related business are fine (although something is wrong since it still won't start when it does - but as you said, I'd lean towards a fuel problem then).

As for the other half of this issue, I have to say, I never ran into the whirring/not-turning-over problem there, but it sounds to me like the starter motor is whirring uncontrolled. Having never take mine apart (when I had one) I am not sure how the starter motor is configured. Anyone know if the gear retracts, such that it could be failing to extend forward and engage the motor reliably (i.e., it's spinning back in its retracted state)?

Does your S50 come with the kickstart? If so, I'd kickstart for now in order to try to diagnose the "real" / primary problem without funky sticky/stripped/whatever starters and batteries in the mix.

If you’re seeing spark I’d check for the presence of fuel. The recording sounded like it caught and fired once or twice, a good sign.

I get that whirring sometimes on my Buddy when the starter gear isn’t fully engaged with the flywheel. This can happen when the battery is a little weak. Doesn’t sound damaged. Agree that if you can kickstart it you can just rule that part out.

Don't forget to keep the battery fully charged in between attempts! If some other part of the system is compromised (e.g. fuel supply) then a partially discharged battery won't help diagnosis.