Modern Vespa

I went for a ride today and I drove about 30 min. around town then on to a frontage road for about 10 min at about 35-40 mph. All of a sudden the engine stopped running (I thought out of gas) but it was slowing a little fast so I put in the clutch incase it was siezing and came to a stop. I let it cool and tried to kick it over but nothing. It sounded normal while kicking it.

I got a tow home and started looking at things. Plenty of gas, oil. I pulled off the spark plug cable and it fell out of the boot. I looked at the wire and it was hollow so I snipped off about 1/3" and still hollow. I screwed on the end and checked if I could see a spark on the tip of the new plug and I saw it sparking. Old plug looked okay maybe a little on the grey side.

I then took off the carb no excess gas on filter but it looked like it was getting fuel. I cleaned the jets, checked the float and all seemed good. Still won't start.

I don't think that the plug wire is supposed to be hollow so I'm thinking it may need to be trimmed more? How strong or bright should the spark be?

Dang, these stories scare me (Newbie P200 owner)

Spark should be a bright blue.
You have spark, though...

What color was the plug?
Check the spark plug wire at the CDI and ensure it's snug.
Does the engine have compression? It should have some resistance when you attempt to kick it over. You've already said it sounded normal.

This sounds suspiciously like a weak/bad CDI or plug cable. What kind of CDI do you have? From my experience (not much admittedly) the Bajaj brand CDIs have less tolerance than Ducati brand (may be a myth, but I'm sticking by it).

I'm hoping that it's the cable. Plug was on the grey side but no blistering , deposits or excessive oil on it. I havn't checked the compression with a guage yet but it seems to be no different while trying to kick it over. The spark on the electrode to the tip was there but I'm not sure other than you saying it should be blue just how bright it should be.

Wangta, The newer later models scare me with all the more complicated later technologie. It's just like working on an older car. Less things to go wrong.

Probably don't need a compression gauge if it has resistance. I was just curious.

The plug being a bit on the grey side isn't that bad, just a bit lean. So long as it's still brownish-grey you're doing okay.

The spark should be noticeably blue and fairly bright. If it's more yellow or isn't too bright, then you're probably not getting enough of a spark. I'd say just get a new plug wire and see what happens. it's cheap enough.

Wangta, P's are pretty much rock-solid if you take care of them but they are old machines so things like this happen.

Thanks for your thoughts and suggestions. That's going to be my next step.

i agree... throw the cheapest parts at it first...

I think you should get some new plug wire and a new cap

And you might be good

You should always change your plug every 1000 miles B8ES is the best all around plug
Always use the best gas 90+octane
Keep the engine case clean so degrease it every 1000 miles also this will also help you see oil leaks and change your gear oil ever 1000 miles I like Castro HD 30 weight any questions send me a message

We sell the plug wire and plug caps (NGK) all should cost you 10 bucks out to where you live

Out in Ghoulie Land AKA Sac

I think I solved the problem. I was having problems with the kill switch. It wouldn't shut off occasionally. After replacing the spark plug it still wouldn't start untill I took off the handlebar switch and put it back on. Now I'm having issues with the carb but that's another topic.

You can always double check your kill circuit by removing the outermost green wire from your CDI. That's the kill wire. If it's shorting out anywhere in the frame it will kill the spark. If you're having spark problems, it's an easy thing to cross off your list.