buddy backfire

[rob_fuel]

Hey guys-

I'm hoping that someone on here can help me with an issue I'm having. A couple months ago, my scooter fell over in the rain. Got pretty wet. Afterwards, it would start up fine, but then stall. A lot. Even during warmup. It was particularly bad when idling to a stop. The throttle would lose its responsiveness, and once the scooter stopped rolling it would just die. I thought maybe it was something in the air filter or the spark plug connection got loose. But then I left town on business for almost a month.

This weekend, before I changed the oil, I started the scooter up and ran it around the block. It started up right away and ran without stalling. It was astonishingly slow, but it wasn't stalling. So I got down to maintenance.

I changed the gear oil and the motor oil no problems (except that the oil change step-by-step thread failed to mention that gear oil smells like rancid onions... I almost puked). After starting it up to check for leaks(none), I also adjusted the idle, thinking that may have led to the stalling. I replaced the spark plug with a new NGK (nothing fancy, same as stock).

The scooter ran great. My top speed was back and the scooter was pulling hard from a stop again. Just like the Buddy I know and love. Monday I took it on the commute to work. Ran out of gas. Pushed it about a block, filled up, and the Buddy was even faster than the day before. Awesome, right? Well, yesterday and today, the scooter's been backfiring and stalling at the first stop after startup. But just then (unlike before, when its stalling was completely random and unpredictable).

Any ideas? Your help would be much appreciated.

[vitaminC]

When you say "it got really wet," what does that mean? Did it fall over enough that it may have sucked in some water?

Maybe you need to drain the carbs to ensure that there's no water in there? Not sure how easy that is on the Buddy.

Could also be that when you ran out of gas, some crud from the tank made it into the carbs...

[Dooglas]

When you say "it got really wet," what does that mean? Did it fall over enough that it may have sucked in some water?

Maybe you need to drain the carbs to ensure that there's no water in there? Not sure how easy that is on the Buddy.

Could also be that when you ran out of gas, some crud from the tank made it into the carbs...

Crap in the carb is always something to think about. I would not think that water in the carb would be an issue two months later but I would check the possibility of water in the air filter. Soggy air filters will certainly restrict airflow and can lead to backfiring.

[KidDynomite]

I've noticed that if I shut the engine off while still pulling into my parking spot it'll backfire.

I'm sure it mainly has to do with the design of the exhaust. I'm not sure where, but somewhere on here a person posted an animated demo on how the exhaust works to reburn before exiting.

[justscooten]

now a motor can backfire from the tailpipe or the carb.
and if it ran faster after running out of gas id check the plug again check its color. it might be burnt a wight ashy color.
if its backfairing from the carb fuel in the carb is lighting up and if its the pipe its fuel in the pipe lighting this sound it might be a timeing issue.
but its been a long time seens small engiens class in high school

[rob_fuel]

When I say that it got really wet, I mean that it fell into a decent puddle. I picked up before I could tell if anything was submerged, though. The real issue was that it sat outside in a torrential (seriously) downpour for over an hour. And then I rode it home.

Nothing in the air filter. Checked it out and it's completely dry. And 90% clean.

If there's something in the carb, would a fuel additive clean it out? Or do I need to take the carb out and clean it?

By the way, thanks for the tips. I really appreciate the help. The nearest dealer is 3.5 hours away.