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Post by crowrobot on Oct 27, 2013 20:29:32 GMT -5
I just bought a used 2005 50cc QINGQI QM50T, and I need some help identifying and fixing some problems. I'm new to scooters, so I apologize in advance for any amateur mistakes.   I bought it for $250, replaced the throttle cable, and now the scooter goes 30 mph on flat ground. It gets from 15 mph to 30 mph really quick, but if I let it come to a complete stop the acceleration is piss poor. It will not idle stably, and dies almost immediately after I come to a stop. I always have to use the choke while driving it. After it warms up I can push the choke in, and it will idle ok, but if I give it any throttle it sputters and dies.Any idea what is wrong with it? or how to fix/tune it up? Thanks for the help. |
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Post by alleyoop on Oct 27, 2013 21:57:21 GMT -5
First What type of carb is that Walbro or what ? And why is the top port open and has nothing attached to it? Also take a picture of the side of the carb the side where the hoses connect. Alleyoop  |
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Post by crowrobot on Oct 27, 2013 22:27:46 GMT -5
I took that photo while I was replacing the throttle cable, so I had the spring and stuff out of the carb. here are some more pics:    |
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Post by alleyoop on Oct 27, 2013 22:36:27 GMT -5
Ah Ok, your normal 2 stroke carb no problem threw me there for a bit sure did not look the common 2 stroke carbs. Well it appears your problem is your carb just needs to be adjusted: Follow this procedure and see if it helps remember the Air Ratio Screw on the 2 strokes are very touchy so just little turns and take your time. Alleyoop itistheride.boards.net/thread/53/2ts-carb-tuning |
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Post by Moat on Oct 27, 2013 22:57:46 GMT -5
A few things stick out, to me -
1) It appears like there's a small section of the carb's attachment flange broken away beneath the lower attach screw in the lower pic - that could possibily be causing an intake leak, and the fuel stains around that area of the flange, black insulator plate and gold-ish intake manifold/reed block further point to a possible leak.
2) Rubber boots are missing from both the choke and throttle cables, where they enter the carb body. These boots could be a source of a small air leak, causing erratic idle/low-speed mixture problems.
3) Rubber intake boot from the air filter, is partially broken away and un-clamped to the carburetor - likely a source of excess (and dirty) air entry, affecting the overall mixture/driveability.
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Post by Moat on Oct 27, 2013 23:04:10 GMT -5
On closer look of the last pic, it just looks like a corner of the attach flange gasket folded up, instead of a chipped flange...
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Post by crowrobot on Oct 27, 2013 23:19:08 GMT -5
alleyoop: thanks for the link. I'll try that tomorrow and see if it helps. I think this might be the solution, or part of it, because the engine always stalls when I give it gas (unless the choke is on):
"1. Give the throttle a quick twist:
A. If the rpms drop below idle speed, then recovers (or stalls), it is [red]RICH[/red] —Turn the Air Mixture Screw Counter Clockwise 1/8 turns at a time and go to #1."
Moat: I didnt know the carb had to be air tight where the cables enter. Do you know where to buy those rubber boots?
Also, the choke cable is kinda loose and doesn't operate very well. Am I missing another piece that would make it fit more snugly?
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Post by alleyoop on Oct 27, 2013 23:33:21 GMT -5
Yes, first check for AIR LEAKS use a spray bottle of water and spray individual areas IF THE IDLE changes when you spray an area you have a leak.
To seal up some of something you can tape it up for a temp fix, another way to MAKE your own rubber cover is get some BLACK ATV GASKET MAKER it turns into rubber after it sets. So you can actually make your own boot on the cable as it sits on top of the carb. Do it after you put it away and the next day it will be good to go.
Alleyoop
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Post by crowrobot on Oct 29, 2013 13:15:16 GMT -5
I tried taping the leaks and tuning the screws, but nothing seems to change the performance much. The screws changed the rpms, but they were still too erratic for me to tell if I was helping at all. While doing this I noticed one of the tubes from the carb isn't hooked up to anything. It just goes about 1 ft. and ends. Could this be the problem? Is this the vacuum port? Where should this tube go to?  |
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Post by alleyoop on Oct 29, 2013 14:23:49 GMT -5
That is the Overflow and Vent for the Carb Bowl here I labeled each of the hoses the one on the right is the Vacuum line that goes to your PETCOCK or FUEL Pumps Vacuum Port to open and close and allows fuel to flow to the carb. Alleyoop  |
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Post by rockynv on Oct 30, 2013 4:29:00 GMT -5
The carb could just be gummed up from lack of use too and may need some cleaning.
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Post by alleyoop on Oct 30, 2013 21:48:22 GMT -5
I tried taping the leaks and tuning the screws, but nothing seems to change the performance much. The screws changed the rpms, but they were still too erratic for me to tell if I was helping at all. While doing this I noticed one of the tubes from the carb isn't hooked up to anything. It just goes about 1 ft. and ends. Could this be the problem? Is this the vacuum port? Where should this tube go to? "The Screws Changed the RPMS"; The AIR RATIO SCREW should change the RPMS that is the IMPORTANT one. That is the Air to Fuel Mixture screw. If adjusting THAT screw changed the RPMS then your carb is ok. Besides I believe yours has a REED VALVE and that may need replacing they do create rips and or holes in the diaphgram and then you will have erratic motor rpms that cannot be adjusted for. The IDLE SPEED SCREW in the center of the carb will always change your rpms but that is just to raise or lower the idle. If that is the screw you just messed that is not the right screw. So I hope you adjusted using the right screw on the carb the AIR RATIO SCREW near the AIR INTAKE of the CARB. If you did that is what it's supposed to do and what you want is to Adjust it to get the HIGHEST IDLE(RPMS) on the center stand. Once you get that then the carb is pretty well set and if it is IDLEING TO HIGH after that you lower the IDLE using the IDLE SPEED SCREW so your rear wheel is not spinning. ON YOUR carb the IDLE SPEED screw is the BIG SCREW in the center of your carb. Turning that COUNTER CLOCKWISE lowers the IDLE and CLOCKWISE RAISES the IDLE. You are not going to get a heck of a lot of performance after the adjustment but the motor will run at its best setting. As far as more speed or lack of power you need to be looking at your CVT weights etc.. and or your motor has lost some COMPRESSION and has lost some power in which case time to rebuild the motor. Alleyoop |
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Post by skuttadawg on Oct 30, 2013 23:06:56 GMT -5
Is the airfilter dirty ? How many miles are on it ? Here is a how to make and use a leakdown tester 49ccscoot.proboards.com/thread/506 A leak will make it not run good . Have you removed the jets to clean em ? How does the sparkplug look ? If dirty get a NGK BRPHIX which is the irdium type which I use |
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Post by skuttadawg on Oct 30, 2013 23:17:54 GMT -5
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..BAD TO THE BONE..
