2011 TaoTao ATM50-A1 I can't figure this out. First of all, this Chinese carb is bull crap. You can't crack the housing to get to the floats. I had to drill out some brass cap to get to the mixture screw. I can't get the carb dialed in to save my life, and am not sure what the heck is going wrong. It has an autochoke...which I hate, and might be the source of the problem. Symptoms: Difficult to start Erratic Idle - Engine spins up with no throttle Bogs down under throttle (typically greater than 25%)...but you can rev it...you just can't leave it WO. I can't figure it out. I pulled the carb and cleaned (what I could) of it. Put it back in, and the same symptoms....hard to start and bogs down at full throttle. Pulled the air filter to get straight air in. Same problem. Sprayed the entire engine with soap to see if I could find any vaccum leaks, and nothing. Pulled the carb again, and drilled out the retarded cap, and went through the full spectrum from lean to rich (to the point that the drain tube on the bottom was dripping gas)...and THE SAME FREAKIN PROBLEM...bogs down under throttle I will say that it has become a bit easier to start since richening the mixture. What the heck should I do? If I should replace the carb...can anyone recommend a good one for under $50? Should I replace the vacuum tubes? This has annoyed me to no end! Thanks for any help!
If this is a new problem then I'd guess the float needle vlalve is failing to shut off fuel flow. Check the seat and seal closely.
I hate anything made in China with a motor in it add an electric choke and It's even worse Can you temporarily option delete the choke ? I just had a Polaris phoenix (built it China) similar problems ended up being the choke . The spring inside it broke the only way to replace it was a new carb body ($329) .. let's just say I used some hillbilly engineering to make it work long enough for the lady to get it sold . She bought it new barely even rode it and it was nothing but problems from day one
The two Chinese 50cc engines I've worked on had absolute crap carbs. Not even worth getting new parts for. The tolerances and quality control are awful. Do some research and look for either a Walbro carb or Japanese Walbro copy if they fit your engine. Should be less than $50. If you have to go with a small Mikuni the price goes up a bit. It's been a few years since I worked on one of these so I've forgotton the details of how I found what fit or not but try googling for scooter forums. Plenty of people that are scooter nutters out there who could tell you what to look for.
Check your exhaust. The little 2 strokes can carbon up or become spooge filled. Just pull off the exhaust and see if it will run better.
i worked on a jeng chin 50 or someething last year that had the pilot hole plugged, did exactly what you're describing. It's a little replica of a honda cub, and actually had a mikuni carb, so take that for what it's worth... The hole was so small, a grain of sand wouldn't fit in it, i'm not kidding. I had to unwind a piece of metal wire from a wire brush and used that to ream out the varnish. I'd suggest a couple day soak in that fancy Yamaha carb cleaner or equal.
Sounds like Rhino is on the right track. The symptoms sound like a lean condition to me. As has already been stated, those tiny carbs are prone to have plugged up pilot and main jets fairly easily so clean the crud out of them and don't simply look and assume that they're clean. Poke a wire, or other suitable tool, through them to be sure. :up:
So I tried cleaning the carb again, and noticed something that might be causing the problem. On the top of the carb is your primary vacuum (I forget what it's called), but it connects to a plunger that controls the primary jet needle. The needle is connected to the jet 'plate' (i believe that's what it's called...it's a little piece of plastic that the needle loosely fits into, and then you slide that into the cylinder that is connected to the vacuum). Well, the 'plate' is a little piece of plastic crap that has a hard time holding onto the needle. I think the needle is probably getting detached from the plate, getting lodged in the main jet. Well, that's the theory anyways. I cleaned out every port I could reach with a wire, so hopefully this solves the problem. If it doesn't...I'll just bite the bullet and get a new carb.
I used to work at a place that was a JinChing dealer and we saw some carbs on new units that would just not work right, period. No matter what we did to the carbs, they ran like crap even though the internals looked new. We finally got to the point that we kept a new carb in reserve as a test unit and would do a quick swap test before we wasted a ton of time trying to figure out what was wrong. Best story is that we had two 90cc quads sold at the same time to the same guy and one was always faster than the other, a lot faster. Owner was pissed, we started swapping parts from one to the other, carbs, exhaust, ign pickups, ignitors, etc...and finally took off the heads for a look inside. One was a 50cc, the other a 90...
Hey guys I thought some videos of what's happening with the scooter might be helpful in diagnosing the problem. Here are a few short clips: Thottle Issues: http://www.youtube.com/watch?v=53vMX3SGfJA Engine Overview (to makes sure everything is connected correctly) http://www.youtube.com/watch?v=4ppi5PQDD9o The ghost rider...engine rev'ing on it's own with no throttle. http://www.youtube.com/watch?v=q3nVPx24Myc I just went on ebay and got this Mikuni carb to replace the POS carb it came with, so hopefully that solves the problem. If it doesn't...next step is to check the valve settings.
This reminds me of the day a customer called the shop and had his mom rev the bike while he held the phone out of the house and wanted to know what was wrong with his bike. Only better
Sounds like the fuel level in the bowl is too low, or it's not getting enough fuel from the tank. I would pull the fuel hose from the carb and catch what comes out while the engine is idling just for grins. If it's getting enough fuel to the bowl then something in that carb is preventing fuel from getting to the engine.. I remember the Chinee carbs having a "mixture control solenoid" and a "mixture controller black box". These two devices combine to force the thing to run lean/burn clean and if one or both fail, they default to full lean...starving the engine.
