What to know about carbs?

[BAC5.2]

My dad might buy a 49cc moped to keep at the beach, just for running around and picking up groceries and stuff.

He's getting one that looks pretty good, but the guy says it doesn't really run. He said he broke a carb cover and that's why it won't start.

What are some basic carb-troubleshooting steps I should take to get the thing running?

I have zero carb experience.

[Brat4by4]

Needles, jets, floats, bah.....

[206er]

1st, see what the problem with the "carb cover" is. is it part of the carb? part of an airbox? that is not a term you really hear and it could be a variety of things.
just inspect for any obvious damage, like follow the fule line from teh tank, throttle cable intact, nothing sticking, etc
if the carb is relatively new, it should be in ok condition. if it was bought at or near sea level, it should be jetted pretty well. but you must remember that it is jetted for the stock intake and exhaust configuration. your dad is probably not into noise and power huuh, so keep the intake system stock for ease of tuning. depending on the carb there may be a mixture screw.
it may be(probably) very dirty inside, and the first step is to totally disassemble it and use a whole can of carb cleaner really going through the jets, all the passages, etc. you might be surprised to see how dirty it is inside. if that doesnt solve it, try rebuilding. a rebuild kit is around $14. be sure and use a small inline fuel filter.
if you are lucky, it will be made by mikuni, keihin, bendix, or some other carb manufacturer that can provide replacement parts.
however if this is one of the cheapo minibikes, keep in mind that replacement parts for a no name carb are not always available. you might advise your dad to go with a honda 80 or some other more common scooter. is 49cc the limit there with no endorsement?

[DLC]

One thing with carbs on motorcycles is that the carb is tuned to take the restriction of the airbox and filter into account. Removing some, or all of the airbox on a stock bike will make it either run very lean, or not at all. The carb cover might be that airbox, and it may not run properly because it's got too much air.

[BAC5.2]

Good points 206er and Dave. Thanks!

I have no idea any info about the moped. Don't know who makes it or brand or anything.

It's only got 2000 miles on it, apparently.

Heres the link. No one buy it!

http://washingtondc.craigslist.org/mcy/153805364.html

50cc is the limit with no endorsement and under 50cc doesn't require registration/insurance. That's what is so appealing about this option.

[206er]

yeah, totally. I want to get a fiddy for the same purpose, but more hooliganism.
sounds like the actual carb isnt the issue.
I would look into the brand of it, and see about replacement parts. oftentimes the little hole in the wall shops are WAY more knowledgeable about these kind of things than big dealers or motorsports shops. if you think you can get the carb problem sorted, it seems like an ok deal.
dont be scurrred of carbs. if you can rebuild trans these should be a snap.

[evolutionmovement]

Try spraying some fuel or somethinhg in it while cranking to see if it starts. That would tell you if it's a fuel issue. Next try spraying into it with carb cleaner and see if that does it. If it doesn't you may be have to take it apart, in which case I'd get a rebuild kit (check on availability). Carbs are really simple. A pump gets fuel to a chamber, a float in the chamber prevents overfilling and the Bernoulli effect pulls fuel from the chamber and into the air stream (which is pulled in by engine vacuum). Venturis speed up the airflow after it comes in through the throttle plates to draw the fuel. Barrels or chokes (European) are the number of these systems per carb.