Maybe this isn't news to everyone, but it may help someone as there are a lot of posts on carb/running problems on these bikes. There is this elusive brass jet UNDER the main jet that is lightly pressed into the upper carb body. To get it out to open up ALL the little holes first remove main jet. Then from the throttle slider hole use a long 8mm bolt to tap the jet flush with the throttle bore. ( It sticks up into the bore about an 1/8 ") Then with a flat tip punch that matches the diameter of the jet without hitting the sides of the throttle bore finish tapping the jet out. It's not in very tight so it should come out with 3 or 4 light taps. There are 9 holes in the ones I've done and usually several are plugged. After you unplug them make sure your adjustable needle on throttle slider doesn't bind in this jet. Lightly tap it back in with a slightly larger diameter punch as the head is slightly larger. Carb will probably need readjusting after installation as former adjustments would try to compensate for plugged orifices.
QT50 carb-The Elusive Hidden Jet !
Re: QT50 carb-The Elusive Hidden Jet !
This is called an emulsion tube or needle jet. If a carb uses a needle then chances are it has one of these
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