Modern Vespa

This a scooter that has sat for the last 3 years before my friend got it. It was running prior to sitting.

Items that have been done:
Empty fuel tank and put new fuel along with a little Seafoam
New spark plug
New fuel valve
New battery
Not a complete carb rebuild but did remove all jets and cleaned them Float working

Scooter cranks strongly but will not catch with one time exception. It did run for a short time, then died. Have not been able to get started again but cranks strong.

Any ideas on what to check/do next?

Check for consistent spark - new fuel and vacuum lines -- put the petcock under vacuum to see if there is steady stream of fuel - remove carb, strip, sonic clean, assembly - check intake manifold for leaks - check air filter. If all this fails to make it start and run, check the valve clearances.

^^^ excellent run down of advice and things to check.

I'll x2 the carb clean. check not only the intake manifold but ALL the vacuum lines to be sure nothing is compromised.

WibDivit,

You're getting great advice. I bet it works. My $.02: If it still has the evap system consider deleting it if only because it eliminates a ton of potential hose or fitting leaks. One little pin-hole leak had Mona hard starting. It took me almost a week to find it. Then I shit-canned the whole evap thing. Cheap and easy, too.

But I'd try those other suggestions first. Those two guys are aces.

Rootin' for you.

Will it fire on starter fluid? If it won't, put the old spark plug back in and try it again.

Greasy nailed it for the one I was working on...
It was that silly rubber manifold.
Didn't look too bad on the outside but you could see the cracks on the inside.
Replaced the manifold and the faulty fuel tap and now it runs like a champ.
It had been sitting for about a year before I got my hands on it.