Modern Vespa

Mine has done two random stalls, not entirely sure why.

Both times happened while feathering the throttle a bit. Once was up a hill, and the other time was during (gulp) lane splitting. Both at reasonably low speeds (between 3-10mph).

The bike would fire up immediately afterwards if I just hit the starter and the brake as usual, but... it is a little disconcerting. Generally doesn't seem to have any other funny behavior, even at normal speed, etc. Go figure.

Don't know what to say. Anyone have this experience?

Twice for me as well. Both when slowing to a stop. After each kill, my mi and F were converted back to km and C. That was at about 2500 miles. I now have 4000 miles and it hasn't done it since. However, most often on colder days, when I start my bike, the display screen goes blank, and my display is reset to km and C. I wish I knew why.

Twice for me here too. Both when slowing to a stop and both on a cold engine. That was about the 800 mile mark and haven't had one since. I'm at 1650MI.

I haven't had this, or any other problem, with my 500, but the symptoms sound like either a bad (loose) ground connection or a loose or corroded power connection.

Ground connections? Question is, where besides the - battery post would a ground wire be? Could it really be difficult to find? Or should it be fairly easy?

I had this problem multiple, multiple times. I talked to JimC once or twice about it whenever people posted about stalling. As best as I could figure, I think it is due to a connection problem with the kill switch. This came from the fact that my stalls came sometimes hot, sometimes cold, sometime slow, sometimes fast, but most importantly I figured out that I could either:

Press down on RUN on the killswitch to stop the stalling for a bit and

That if I actually killed it mid movement and restarted it on the fly(or just switched back to RUN if going fast enough) it would usually stop the stalling for the rest of the day.

Here's the good news, my stalling seemed to 'peak' around 700-1000 miles and since then has virtually stopped. Once every blue moon or about every 700 miles it might do it once during the day, at which time I quickly just press down and hold the RUN for a bit and the bike straightens out or I kill it and restart on the fly.

Thanks for that tab bit of info. I'll look into that. unfortunetly we are supposed to get 6 inches of snow tonight. I'm not looking forward to putting away my machine just yet.

I had a stall tonight and it left me stranded on a busy (50mph) road in rush hour. Huge step up to the side walk so I could not get it off the road. I was sitting there for 5 minutes before I got it going again. Not nice!!

Got it home safely and tried stopping/starting it. Most of the time I would get no response when pressing the start button, sometimes it would splutter a little bit and then die. I figured it was something to do with the kill switch so I pressed down on that as I tried starting it and it fired up every time. Soon as I let go of the kill switch it would splutter and die. So there is definitely something wrong with the contacts. Time to call the shop. I'm glad they are only 6 miles away! Meantime might have to carry some duct tape to hold that sucka down.

got my kill switch replaced under waranty today. The guy could tell there was something wrong with it just by the amount of movement in the switch. Took a total of 15 minutes or so and I was on my way again

I too am a victim on my 400. From what I can figure is this is a MFG defect on the timing for ignition. Does not happen often. After all this is only one cylinder, there are no others to keep it going. You would think though that the revolution of the motor would be enough to keep it running but NO. So maybe you guys are right, maybe it's the kill switch acting up once and a while. It only happens when I go to accelerate when I'm off the throttle. It has happened at idle as well. This is not a common thing on a daily basis and I think only happening to the big cc engines.

started happening around 700 miles. it stalled out twice when coming to a stop on a cold (by LA standards) day. started up immediately. this just happened so i don't know if it will be a continual problem; but, will keep an eye on it.

Happened to me this morning after getting off the highway. While the bike was decelerating with the throttle closed, the engine popped a bit (could be unrelated), then stalled. I had to come to a full stop before the starter would engage. Then all was well. Never touched the kill switch, and the fact that the oil pressure warning light went on after the stall seems to suggest that the ignition circuit remained on the whole time.

This did happen once before in a parking lot, also a minute after leaving the highway and with closed throttle. Started up again fine.

If this were a carbureted engine, it would probably be icing. Come to think of it, the conditions were perfect for icing this morning (about 55° F and very high humidity). Is it possible for a FI engine to ice? Are there any restrictions in the intake system that could produce the Bernoulli effect?

This has happened twice on my MP3 250, during normal riding. It started right back up, but freaked me out.

It happened to me today on a city street, no one behind me, I was doing a slow acceleration. The engine had been warmed up on a 35 mile ride and I had just turned it off for about 5 mins before cranking it up again. I moved out of my parking spot and started to slowly accelerate up the road, and that's when it stalled.
It did start right up again. I've got about 3k miles on this beast and if it happens more often, it may be time to ride another brand. 8)

Before giving up on it, have the dealer look at it. Mine did this 5 or 6 times, but I understand that with new technology, someone has to be the 'guinea pig' in exchange for all the fun and curiosity of it. Mine turned out to be a simple killswitch connection. One way to tell is if it does stall again, press down hard on the RUN side of the killswitch and see if that ends the stalling. I did this and figured it out. I also noticed that if I stopped it using the killswitch and restarted it while it was moving down the road, it would stop stalling for the rest of the day or so.

Moral, in normal daily use leave that killswitch alone! Always the advice this side of the pond, though I understand for infathomable reasons the advice given more to the West is different...

I don't use the kill switch in my daily driving, but will start to notice it more now

I didn't use it in normal daily use, and can't see any reason why someone would. My 500 stalled about... let's see 6 times before I finally decided to press a little on RUN while it was stalling to see if the killswitch was malfunctioning. It was, because this stopped the stalling without having to kill or stop the engine. This led me to take it to the dealer who fixed it and I since haven't had a stall nor touched the killswitch.

I agree, except for abnormal conditions, I would leave the killswitch alone as it apparently has contact issues straight from the showroom.

The problem as I see it is that the switch has to be 'good' in the Run position, as well as killing the bike in the 'Off' condition. Remove the former, job done. Too many interlocks...

Icing is not restricted to carb engines, but is not normally encountered on bike or scooter engines. The carb or FI body sit behind the hot engine and so don't get as cold as they might otherwise.

With scooters the bodywork retains hot air around the fuel delivery system and so icing is not common. The conditions under which icing might occur in a plane are also different for a ground-based vehicle...unless you are very, very high up.

If it was icing, you are unlikely to get going again for quite some time - well, that was the case on any system I saw iced up. The ice literally had to melt before the engine would run properly.

Cheers, and all the best

Trevor G