Modern Buddy

So just to quickly sum up. Purchased scooter in beginning of Jan. Have about 550 miles on it now. First service done at 400.

So to preface my issue has been happening since I started driving it. Usually in the cold but today is awesome weather and still did it.
What happens.
1. I come to a stop sign or traffic light after running at 45 to 55 mph about 5 to 10 miles. Stalls. Engine slows down and just turns off. No sputter or cough just shuts off.
2. Starts right up and has no problem. Drives fine. No loss in performance.
3. Do not think this is vapor lock because it starts right up and gives me no trouble at all.

I asked the 2 scooter mechanics about it, they suggested
1. Scoot was not warmed up properly. (I do usually warm it up until the idle settles, sometimes not and when I do not it does seem to happen, but should this even be a issue. I drive at 30 mph for at least 2 miles before getting into a stretch where I can open her up.)
2. Scoot may have a fouled idle jet. (The scoot idles just fine when I am letting it warm up and at every stop sign or traffic light before the stall and thereafter)

Maybe this is not a big issue, it really doesn't bother me much just thought it was sorta odd. Wondering if anyone else may have this. It does not stall any other time but those conditions above.

Thanks

Unlikely to be vapor lock, because it starts so easily.

I'd go with fouled jet, but it may just be that the idle is set too low. The idle runs fast at first, then slows after warm up and should be set when the scooter's warmed up.

See: topic4153.html#46188

How 'bout the "Stall of Fame"? Vent the gas cap.

Karl

Thanks Karl, I did checked the Stall of Fame and other stall threads and from all the description of Vapor Lock, this sounds nothing like it. No loss of power, does not stall when I am moving.

Thanks Eric for the link. I will do a quick idle adjustment and test. Maybe the auto choke on warm up does fine but it idles to low after engine is warmed up. Looks easy enough to do.

rfman81 wrote:Thanks Karl, I did checked the Stall of Fame and other stall threads and from all the description of Vapor Lock, this sounds nothing like it. No loss of power, does not stall when I am moving.

Thanks Eric for the link. I will do a quick idle adjustment and test. Maybe the auto choke on warm up does fine but it idles to low after engine is warmed up. Looks easy enough to do.

Sounds like you're on the right track already.

yeah just turn the idle screw in half a turn and see if that fixes it ...I'll bet that takes care of it.

If not, try draining the carb ,too. There could be a little water in the bottom of the float bowl. Doubt it, but an easy thing to do.

Did you buy it as a new scoot from a dealer? Take it back and let warranty fix it. I fiddled with my Fiddle getting the idle correct; turned out to be the auto choke which needed replacement.

make sure battery good and strong ,I Use a battery tender
all winter, winter is rough on batteries also change spark plug
had same problem

david12df wrote:make sure battery good and strong ,I Use a battery tender
all winter, winter is rough on batteries also change spark plug
had same problem

Thanks for the input. Battery is only about 3 months old as I bought a new battery when I bought the scoot. I ride just about everyday even in the winter. But I will get it checked as my commute is about 5 miles so from my reading it is not enough to charge the battery back up. But would a low battery cause it to stall once in awhile after coming from a hard run?
Spark plug was replaced at the first service and it did the same thing before the first service.

Mine does something similar, maybe even exactly the same. Sometimes, when I stop, and just occasionally when I slow down a lot, it just dies. When it dies, it makes sort of a "chunk" sound - pretty abrupt. It's always done it. I bought mine used with 1,000 miles on it and it had been dropped by the previous owner. At one point, when I had the Genuine dealer service it, he thought maybe it was electrical, but that's just because he noticed the physical damage from the drop was on same side where most of the electrical is. He asked if I wanted to leave it for troubleshooting, but it sounded expensive, so I declined. He turned the idle up to compensate, but it was too high, so I turned it back down. I've been riding it this way for about 2.5 years now and I'm just used to it. In fact, now that I think about it, I've become aware of the symptoms, so I just give it some gas when I notice that it's about to happen and that usually prevents it. It doesn't happen a lot and when it does, I just start it back up and keep going. No big deal. I've got over 8k miles on it now and it's never gotten worse.

My Ural is doing the exact same thing right now. Must be a bad time of year for carbs.

~SM

Happened again tonight. Not on my way to work this morning or the way home. It is pretty much like pdxrita says. I still haven't opened the scoot up yet to adjust the idle. However, I just give it some gas and it stays fine. However my scooter has not been dropped and I am the first owner.

I have decided I think it is the idle. I will adjust and update everyone here once I get around to it.

I've adjusted my idle mixture screws also, but I haven't gotten a chance to test it out yet. I wonder if it has to do with the weather. As the temperature swings back and forth, it changes the amount of oxygen in the mix (ex. higher temps, gas expands, less oxygen fits inside the combustion chamber). Fuel injected engines compensate by adjusting the fuel mixture automatically. Our carbs can't, so it stands to reason that if the carbs were adjusted during warm or cold weather, the mix will eventually become out of whack as the seasons progress.

Just a theory.

~SM

rfman81 wrote:Happened again tonight. Not on my way to work this morning or the way home. It is pretty much like pdxrita says. I still haven't opened the scoot up yet to adjust the idle. However, I just give it some gas and it stays fine. However my scooter has not been dropped and I am the first owner.

I have decided I think it is the idle. I will adjust and update everyone here once I get around to it.

I really have no idea if mine was caused by the drop. As far as I can tell, the damage from that was all cosmetic. Over the time I've had it, I've replaced most of the damaged panels and never observed anything amiss underneath as I removed the old stuff. When my idle was turned up too high, it did prevent it from happening, but I could still feel/hear that little hesitation trying to happen every now and again. But the mechanic had it turned up so high that it wanted to move while stopped. I'd rather deal with the stalls than have to fight to keep my scooter stationary at a stop light, so I dialed it back down to normal. But fiddling with the idle a bit is certainly worth trying, and it's just about the easiest thing you'll ever have to do to your scooter.

Swordsman wrote:I've adjusted my idle mixture screws also, but I haven't gotten a chance to test it out yet. I wonder if it has to do with the weather. As the temperature swings back and forth, it changes the amount of oxygen in the mix (ex. higher temps, gas expands, less oxygen fits inside the combustion chamber). Fuel injected engines compensate by adjusting the fuel mixture automatically. Our carbs can't, so it stands to reason that if the carbs were adjusted during warm or cold weather, the mix will eventually become out of whack as the seasons progress.

Just a theory.

A good theory. Temperature changes can throw off the idle.

In seasons when it's cool and you heat the bike while riding or as the temp warms up during the day, settings for things like the idle screw can get wonky due to parts expanding/contracting.