Modern Vespa

This weekend my buddy and I went to the Mountain Meadow Mayhem Rally in Salt Lake City. Since getting the LX back from the shop, it's had a problem where it won't idle. It just dies. After nearly two months in the shop, the owner (he was at the rally) thought it was fixed. He's a good guy and really put a lot of time into her. In the shop, after completely cleaning every bit and testing, got her to idle fine. However, after bring her home, the bike still dies when idling. The ride to the rally from Ogden is about 50 miles each way and she did great cruising at highway speeds but when we stopped....pfft.

On the way home, same issue. Ride, cruise at 55/60 without issue. However, pull up to a stop light and dead. She started without issue and as soon as I'm moving, she runs fine. However, after 100 miles, she had had it. As I rode onto my street, the LX just up and died. I couldn't turn her over I thought, this is the end, I have burned up the engine (though no oil light, check engine light or other light was illuminated).

Fortunately, the ride home is a downward slope and I just coasted home. This morning, I went out fearing the worst. But to my surprise, she started right up and even idled a little before dying. My guess is that with a low tank, the 90+ degree heat and the other issue causing the idle problem I got vapor lock. After a nice cool down, she's at least running. So...while I had a lot of fun at the rally (won a bunch of stuff in the raffle which never happens), I also had a lot of stress.

BUT WAIT,...it get's more interesting....I am home after 100 miles of riding and my wife asks me to run to the grocery store. I think the LX might be dead so I will take the Sprint to the store. As I ride, my clutch cable slips and now I am stuck in second gear. I am still able to ride (albeit slowly) and the store is close. I just pop on over and then give it a good bump start to ride it back. In addition, I was so pleased with myself as I got the lights working but sure enough, 15 minutes on the bike and they another bulb is burned out so they don't work.


I still feel like the luckiest guy in the world as I didn't break down in either case and made it home safely. But I am confused as to why I am having these issues. I'd welcome thoughts on this idle issue.

Thanks!!

What is usually called "vapor lock" on a scooter is actually a tank venting problem. It can occur after the bike has run for a while at higher speeds and temperatures. It is immediately remedied by loosening the fuel cap and allowing air into the fuel tank. Your symptoms do not sound like "vapor lock".

Hi,
I had a very similar problem, i was ready to pour petrol on the mother and touch it, checked everything, then i found the problem, valve clearances even though i had checked and re checked, it turned out to be faulty Chinese fleabay 50c feeer gauges, they were stamped with the wrong sizes,
$10.00 and a decent set of bluepoint gauges later idles like a champ
Moral of the tale check the valve lash
Cheers Andy

I think what you described is EXACTLY what happened when it died. However, it's obviously unrelated to the idle because that happens even when it's ice cold...in fact, it works better when it's cold.

A crazy thought and easy to check - vacuum hose from the petcock to the intake manifold. If it has a wee leak, at idle it may not be enough vacuum at idle to cause a gas flow. At higher revs, more vacuum, maybe enough to over come it. If this is the cause, change out the fuel line as well while you're there. If this is not the cause, I would look toward some wonky wiring.Take the under seat storage out and look around. Take a few pics and post them up, maybe someone will see something that is not right.