QT50 - Carb Issue

My 1987 QT50T sat unused for 5 years with gas in the tank and carb :{

I cleaned everything like new, ordered a carb rebuild kit with a new float/needle valve and replaced the spark plug.

The engine runs but is slow and sputters like the mixture is way too rich. Seconds after shutting off the petcock the engine revs to full speed and then quits of course.

Does anyone have any ideas?


Re: QT50 - Carb Issue

yep the rpm's pickup as the float empitys an for the rich mixture are you running a stock airfilter? and did you spray the carb or dip it cuz the airway by the air screw likes to get gummed up I also suggest filling the tank half way and scrubbing it with a bottle brush then draining the fuel by removeing the petcock and filtering it doing this a few tiimes till it looks clean (its easyer then taking it off and doin the nuts and bolts thing) find a friend with a drum of carb dip and let it soak for 24 hours or so (take off everything plastec or rubber remove the air screw idle screw and float first ) then flush it out with water and compressed air. I did this for my qt it had the same problems sat for 20 years, now it runs like a champ.

Re: QT50 - Carb Issue

oh yeah and add a filter somewhere in the fuel line it will save your ass in the long run.

Re: QT50 - Carb Issue

I did spary it but I thought I was pretty thorough (maybe not).

I did add a fuel filter after I saw what was in the tank.

Had to clean and flsuh everything including te gas cap.

I am running it without an air filter for the moment.

I'll soak it in a tank and see if that does the trick.

Q: Where is the "air screw"?

I see two screws and am not sure to which one you are referring...

Re: QT50 - Carb Issue

the two on the side the one that sticks out more is the fuel (idle) screw, recessed one is the air scrwe . after sitting that long it relly needs to be dipped / blown out or boath (predurribly both) with out the filter you wint be able to properly set the idle and definately do not ride it without a filter mikunies (your carborator brand) relly dont like it if you want if you want to do some Q and A I can give you my #.

Re: QT50 - Carb Issue

where the fuck did I learn to spell?

Re: QT50 - Carb Issue

lmfao I do that sometimes..analog brain in a digital world!

Re: QT50 - Carb Issue

and how.

Re: QT50 - Carb Issue

Hi Chris,

Disassemble your carb and look at the main jet. Directly behind that is another jet that, if plugged, will cause exactly the symptoms you describe. Remove and clean both jets (the smaller one takes a smaaaalllll screwdriver!), reassemble, and adjust you idle screw if needed. As mentioned, thoroughly clean the tank and petcock and add an inline fuel filter or you will repeat this process again and again.

Good luck,


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