50cc keeps bogging, wont stay running.

[D2coupe]

I have a Tank urban sporty 50cc that I got from my brother inlaw. He used it as a rental at his hotel, and when I got it, the speedo didnt work and the battery was not keeping a charge (just enough to get it started, but not always). He told me that he let a long term tenant at the hotel borrow it and she may have modded it (no speed limit screw on the throttle).

We used it around our community for 3 or so weeks and then it began to develop the problem, starting every once in a while and today 5 times with in a mile. It will start fine, but idle uneven. It will accelerate, but once it gets going it will slowly die out, losing rpm until the engine cuts it self out.

Im lost as to where to start, so please, any suggestion would be great.

[Fox]

Check out these free manuals!  They're all good info:

http://www.chinesescooterreference.com/manuals.htm


 

[D2coupe]

Thank you for this, there is a lot of information in here. Where would you start? seems like it could be the fuel sending unit, or maybe the auto choke, a clog in the fuel line. Maybe bad suction from air box? I really dont want to spend a ton or tear into a motor ive never worked on before.

I have all the tools needed beside the ones for a valve job, so im hoping i can avoid that.

[goosestale]

 The only special tools needed for a valve adjustment are a set of feeler guage's, $7 or less from an auto parts store like O'Reilley's. Not a difficult thing to try, and if you are keeping the scooter, something you may need to do periodically. What do you mean by no speed limit screw on the throttle? Do you mean the idle adjustment screw on the carborator?

[scooter 49]

First thing i would do is replace the fuel filter if it has one on it.
If that does not do the trick then I would remove the carb and clean everything inside with carburetor cleaner.
You say it starts right up with no problem. Does the engine idle high at first startup and slowly idle down?
If yes than your choke is okay. You sound like you do not want to mess with it too much. I am afraid you will have to mess with it if you want it fixed. It is obviously not going to fix itself. The things I mentioned above are not too difficult to do and if you have basic tools it should be no problem.

[D2coupe]

First thing i would do is replace the fuel filter if it has one on it.
If that does not do the trick then I would remove the carb and clean everything inside with carburetor cleaner.
You say it starts right up with no problem. Does the engine idle high at first startup and slowly idle down?
If yes than your choke is okay. You sound like you do not want to mess with it too much. I am afraid you will have to mess with it if you want it fixed. It is obviously not going to fix itself. The things I mentioned above are not too difficult to do and if you have basic tools it should be no problem.

I will get a new fuel filter.

The scooter will start up with in 5 kicks, battery is completely dead, but if its on my charger, the scooter will start with the electric started. The bike does idle out, but the bigger problem is:

I will be doing down the road at wide open throttle, and slowly lose RPM until its dies out completely. Sometime it will run fine for miles, sometime is will run at very low RPM, but not die and but most of the time it will just die. I have also found that after the first time it dies, it actually runs better when started back up via kick start.

[D2coupe]

What do you mean by no speed limit screw on the throttle? Do you mean the idle adjustment screw on the carborator?

From picture on the forum, ive noticed that i do not have a limit screw to limit how fast it can go which should be located on the throttle connected to the carb.

Ive worked on cars before, but never anything with a carb or anything this small, so if my info isn't correct, please correct me.

Thanks again

[goosestale]

 The screw that is on the top moving, is a restrictor. If that is missing you don't have a problem. The other one on the right that is stationary in the picture is the idle adjustment screw, if that is missing you have a problem.


 Your scooter doesn't just die suddenly, so probably not a spark problem, though check your connections to the spark plug and coil for looseness. Wouldn't hurt to replace the old spark plug. $3 or so.
 I agree, replace the filter, and clean the carb. The jets may be clogged from bad gas or sitting for too long in storage...try fresh fuel too. The battery will need replacing eventually when you get it dependable enough to want to spend the money on it. Though if you are going to be storing it soon for winter I'de wait till spring on that.
 
 

[scooter rebel]

The experts have spoken and they normally hit the nail on the head.

Now my plan would be first as suggested, get a new fuel filter (sounds to me like what you need), and then add some sea foam to the gas. If you have a little clog in the carb Sea Foam often times will make it go away. It is a lazy guys way to try to fix a carb. The dose is one once per gallon, so about 2 ounces in a full tank. Start it let it run to get the treated fuel in the carb and then let it do its job, soak for a few hours, like over night. If that does not work go ahead and take the carb apart.

just an opinion.

[D2coupe]

Today I:

Checked all connections, checked the fuel lines, check the oil return line, adjusted the Fuel volume regulation screw, adjusted the Idle screw, changed the oil, replaced a bad fuse and add fuel treatment to clean the carb. After all this fun stuff, the bike is running very good. Just need to find the sweet spot on the idle screw.

bike doesnt stall and idles evenly, not sure which thing did the trick, but thanks for all the help.