Question about 2002 Yamaha YZF-R7 OWO2

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I have a 50cc moped qt jinlun i just bought anew carb when we start it, it run for a while then just dies as if starved of petrol i know it works by a vacuum it will go down the street for a minute then die we **** petrol back in to the carb then it wil go again for a min the floats not jammed, but when we do start it it revs like mad for a while if we diconnect the automactic choke it makes no difference what i do know is these bikes are total rubbish and for anyone out there buying one dont bother get a yam suzi kawa or honda but dont buy one of these mine is only one and a half years old and the jinlun makers are not in the slightest of any help they just told me to do an oil change lol ,yeah right whats that got to do with my carb

Posted by euphoric38 on


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Louie Role

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Hi and welcome to FixYa,

To my understanding, most of these China made scooters uses a vacuum controlled cut-off fuel valve. Vacuum is tapped either from the carb out or intake coupler to activate and allow fuel flow; no vacuum no fuel from tank. Possibilities are:

  • no or little vacuum to allow fuel flow;
  • vacuum controlled cut-off fuel valve faulty.
A workaround is to install a manual cut-off or bypass it entirely.

Incidentally, the 'revs like mad' is a result of slight overflow when fuel first flows to a starved/empty carb bowl.

Good luck and thank you for using FixYa.

Posted on Apr 20, 2009


richard hopkinson

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Retro scooter packed up one night on the way home.disconnected side stand switch runs better now than when I got it. and its a 2012

Posted on Mar 04, 2013



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Adjust your valves.
as jinlun motors wear the valve clearance closes.
thus when it warms up there will be no compression.
and act's like its out of gas..

Posted on Mar 13, 2010


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4strk50cc new cdi coil and carb still wont run for long whats next

Posted on May 20, 2009

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best regards savumihai71

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