QT50 stalling/carb overview

Timothy Griffin /

Can anyone help w/the carb on a Yamaha QT50? 1987?

I've taken it apart and cleaned it good (carb).Airfilter changed.

But no matter how high I crank the idle screw..it stalls.

It runs a little better on "start",but stalls real easy on run.

I had it idling for a bit on "run" but after cruising around a bit it wont idle again.Just bought it today...750 miles!

Re: QT50 stalling/carb overview

There are two screwa to adjust the idle. One is the idle stop and the other is the adjustment. The idle stop is the larger of the two . It just keeps the barrel from closing. The other one is adjusted until you get the fastest idle and then lower the idle stop until it is idling where you want it to. Try that and see what happens. Also clean and gap your plug.

Re: QT50 stalling/carb overview

Timothy Griffin /


(6v light appears on forhead)

The main adjuster is closer to the intake pipe,

and the set screw is closer to the box?

Also- how is mixture determined on this? Or is it auto?

Thanx man? My fiancee' is very appriciative.We both just love this little beast,now named Yoko.

Re: QT50 stalling/carb overview

Timothy Griffin /

Sorry for the posts...just got back-

I see how that works..(screws)..It seems to waver up and down (idle)all over the place by itself ..too high then to low. (i checked the throttle cable & sliding plungers attached to see if their hanging up- they seem really clean)


Re: QT50 stalling/carb overview

How is the air cleaner? with the motor idling adjust the idle adjuster for the fastest idle and then lower the idle stop. Start at about 1 1/2 turns on both.

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