Yamaha TW 200 starts but won't run.

have you left the choke open ? this mixes more fuel to the engine upon starting but will stall it if left open too long . check your fuel filter too it may be full of debris.

On electronic fuel injection pumping an pumping an pumping the gas pedal does nothing without the engine running ! Pushing the gas pedal to the floor will cause the PCM - engine computer to go into clear flood mode .

You have some very interesting ideas here , but not really how it works or is !

The vehicle will go into closed loop fuel control when the engine coolant temp reaches a definded temp an the O2 sensor get hot.

She would run for a couple minutes and die which is open loop when running, closed loop is when the sensors kick and it would die. Pulled spark plugs, they were black meaning no spark. Can only be 2

Black spark plugs indecate a rich condition , over fueled , wet spark plugs indecate no spark .

It should start easily, start with fresh fuel/oil, pump the primer as many times as it takes to 3/4 fill the bulb, pull the choke fully out, crank the engine until it fires once, push the choke fully in and crank again until it fires up, after re fueling a warm engine, pump the primer again until it 3/4 fills the bulb,before cranking the engine pull the choke fully out and in again( this will engage the part throttle ) then crank the engine until it fires up.

u can set it lesser or more to help cease the sputter but it needs a pro ajust or cleanin--u may be able to doit urself-ther are books

If the choke has to be on for the engine to run then there is a lean fuel mixture problem, and chek for a loose carburetor, intake bolts, dis-connected or missing vacuum lines/caps, or damaged carburetor or intake gaskets. Also, the engine idle rpm might be too low, the air/fuel mixture might be too lean, or the carburetor could be plugged up internally.

have fuel injection system cleaned

Pull the float bowl caps off the carbs and then spray carb cleaner into the main jet and all other accessible ports on the carbs. Chances are there is a build up of water condensation in the carbs.

Hi
I have been working on my carb today,the pipe from the bottom of the carb should just run down by the bottom of the swinging arm,there should be another pipe from the pipe on the left side of the carb just above the fuel intake which also runs down to the swinging arm and connect to nothing.
Cheers