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I'm having an old model TVS Scooty ES, as the petrol was chocking while entering into the carburetor.

After cleaning the carburetor and replacing a new spark plug and I had neither rotated the Air/Fuel Mixture screw nor the Idling screw in the cleaning process. Here the pilot jet is fixed.

Whenever I tried to start the scooty, it idles for a while, but as soon as I open the throttle to move forward, the engine was turning off. By applying the choke for a few seconds & opening the throttle, the engine was running good and after releasing the choke, the engine stops suddenly while accelerating, without accelerating it would continue to remain to stay in the idling mode. So I tried to adjust the Air/Fuel mixture ratio by rotating it clockwise letting more fuel to enter into the carburetor. Partially the problem was solved.

On the road when I begin to accelerate constantly, fuel was chocking So I screwed in the Air/Fuel mixture screw completely in(making no more rotations possible), but no good still I'm facing the same issue. So checked the spark plug color that was turned to brown. So still the fuel consumption was lean.

On inspecting the pipe coming directly from the fuel tank to the petrol filter as I could see the fuel was dripping with a mixture of petrol & air.

So I need to figure out the cause whether the problem lies in whether with the Air/Fuel mixture or from the fuel dripping towards the petrol filter or from the throttling piston?

Specifications:

Engine Displacement 59.90 cc
Engine Type         Single cylinder, 2- stroke, forced air cooled.
Engine Starting     Electric/ Kick start
Maximum Power       3.5 bhp @ 5500 rpm
Maximum Torque      4.5 Nm @ 5000 rpm
Top Speed           75 kmph
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It's definitely a fueling issue, which puts it right in the realm of the carburetor.

You said you cleaned the carb, yet didn't touch the screws. There's no way to thoroughly clean a carb without removing the jetting screws. Most carbs are setup to adjust the screws in all the way, then back them out 1.5 turns. This puts it in the ballpark, so there shouldn't be an issue. You could also just bottom the screws from the start, counting the number of turns ... then when you put it back together, put the screw in the same amount as it started with. This will put you pretty much right on the money.

Bottom line, you are either going to have to take the carb all apart again and thoroughly clean it, or replace it. Just about no two ways about it.

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    Yes, your right. Since without removing the Air/Fuel ratio screw I had cleaned it for twice without causing any issue. But now I had cleaned, removing the Air/Fuel ratio screw and most importantly I had eliminated the air coming from the fuel dripping towards the carburetor from the petrol filter. Now everything went quite simple and the issue had been solved. – Nishanth ॐ Jun 24 at 5:07

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