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A friend wants to sell me a scooter for a very cheap price. It is a Chinese model (Qingqi QM125T-10M). Probably a 125cc machine.

He tells me that the scooter worked fine and he used it to go to work every day until he lost the key. The scooter was without use for about 8 months. I have already a new key and I filled new petrol into the tank (which was nearly empty) but the problem is the following:

Turning on the engine is very difficult. After several trials it may run instable (about 1000 rpm - 2000 rpm) for a short while but then it turns off from alone after 3 to 30 seconds. I cannot find a choke.

When it is running and I accelerate, it turns off immediately. It is impossible to make it run faster than stand-by speed. Accelerating kills the motor.

The petrol filter seems to be OK. When pulling the flexible tube a lot of pertol flows out.

I have the following questions:

  1. What is the most probable cause for this?
  2. Can the cause be that the machine was not in use for some months?
  3. Is it true that petrol may "become old" after some month so it does not burn anymore correctly?
  4. How high is the difficulty to repair this (clean anything inside, change spark plug) or do I need a garage for that?
  5. Does anybody know where I can get a service manual for that model?
  • 1
    See this answer about lawn mowers. Mowers are simpler machines, but the carb on you scooter probably does have some degree of clogging. – JPhi1618 Jan 18 '16 at 19:32
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    I can't find anything on this model. I would like to know if it's a carburetor or fuel injection. With your response I can tell you where to start regarding troubleshooting. – DucatiKiller Jan 18 '16 at 23:59
  • > carburetor or fuel injection. I don't know. – Elmue Jan 19 '16 at 4:42
  • Can you take a photo of the throttle body or carburetor and post it? Help me be successful :-) – DucatiKiller Jan 19 '16 at 6:48
  • Pretty much sure its a carb :-) Never seen a Chinese scooter with EFI , if this is EFI , i will be damned !! and it would be the first. – Shobin P Jan 19 '16 at 14:13
4

Based on my limited knowledge on scooters courtesy of owning one for about 3 years and assuming your scooter is carb and has similar mechanism (BTW not able to Google your make and model it's rare)

  • First of all check the carburettor. If the carb is blocked then you will notice the symptoms which you have mentioned , blockage at higher throttle.
  • Check the Air filter: if the air filter is blocked then you will encounter similar issues.

The above two are very easy and basic checks which can be performed by a road side mechanic or by yourself. Should not cost much including labour.

In case your vehicle is still stalling after all this then I would suggest taking it to a proper mechanic and getting it serviced. As for my experience with scooters , they dont cost much in my country (India) to get serviced.

Also, if its a 4 stroke scooter then there are chances of the choke not being there in the vehicle , some scooters dont have chokes, mine had one but I have seen without chokes.

3

What is the most probable cause for this?

In the most general terms, the engine isn't running because there is either too much air or too much fuel.

Can the cause be that the machine was not in use for some months?

Is it true that petrol may "become old" after some month so it does not burn anymore correctly?

It is possible, especially if the fuel didn't have good-quality stabilizing additives in it.

How high is the difficulty to repair this (clean anything inside, change spark plug) or do I need a garage for that?

This depends on what the problem turns out to be.

Does anybody know where I can get a service manual for that model?

Google is not likely to help you since its services are not permitted in China. The source for such information is also unlikely to be readily available outside of China.

2

It really sounds like your main jet is clogged. You can loosen the hose clamp holding the carburetor, then twist the carb a little to break it loose from the intake. Take pictures or tag all hoses and electric choke wires then remove them from the carb. Lay an old towell or white rag on your work bench. Turn the carb upside down and remove the float bowl. In the center of the upside down carb you'll see the main jet (brass cylinder). Use a clean strand from a bicycle brake cable an clean the hole all the way through the main jet. You'll have to hold the sliding cylinder so that the carb throat is open. This is so that the strand of wire itself passes into the carb throat. Use WD40 in the jet in case its really dirty. Carb cleaner will destroy rubber seals and the rubber throttle slide skirt inside the top of the carb. Carefully reassemble the float bowl and reinstall the carb and its hoses. Good Luck.

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