I have a Kymco Quannon 125cc from 2007, I bought it last year. Some time ago I was having problems when I tried to start it. The bike does the regular noise when starting it, but seems the gas is not ingniting. At first I thought it was the battery but changed it and does the same. If I start it by moving it and accelerating in 2nd gear it starts but the ralenti is not stable and ends up turning off.

What I have done:

  • Change battery to a new one
  • Change Oil
  • Change spark plug

Im thinking in cleaning the carburetor but I don't know if the problem can come from there or not. If anyone has any possible idea would be great.

If it end up starting and I keep accelerating until the motor is warm, it works perfectly. I can switch it off and it start properly from starting button, until its cold again, that problems come again.


After carburetor cleaning the problem persists, might need a valve allignment, but will go to the garage to do it. Unless I have any other suggestion to try before getting it into the garage.

  • is it carbureted engine? May 28, 2019 at 13:06
  • yes, it is carbureted engine
    – Ivan
    May 28, 2019 at 13:06
  • did you ever mess with the carburator. My amateur guess would be issues with idling part of the carburator. You see there are different jets and adjustments for fuel delievery when you are idling and you are giving gas. If the idle adjustment is wrong or the idle jet is clogged, it might be the reason why it will run but not idle well. However, I would look for other simpler reasons before messing with the carb. May 28, 2019 at 13:16
  • No, I have never messed with it. So the adjustment should be ok, because it has been like that since I bought it. And only the last month has been like this.
    – Ivan
    May 28, 2019 at 13:19
  • 1
    You should obviously try to find an owner's manual or even better a shop manual for the bike. Two generic videos on the issue I know are, youtube.com/watch?v=6_EXK7RpKMM and youtube.com/watch?v=p44VNddZ7Zc May 28, 2019 at 13:49

1 Answer 1


Finally after a long time without answer. The problem was derived by the carburetor. The problem was due to:

  • Dust in carburetor (a lot! persisted after cleaning with carburetor cleaner spray, without dismounting, sprayed it through air entrance)
  • Previous owner thought he was a mechanic. My mechanic said it is in very very bad conditions.

Solution: Full cleaning until the new carburetor arrives to change it.

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