2008 TTR 50 yamaha will only start when starting fluid is sprayed in carb ...and won't stay running

Fire meaning run a second ok spray bottle w gas in it and air filter box tube off carb inlet have assistant to crank on your command.. spray 4 pumps of gas into carb inlet w grip wide open close grip have assistant crank bike if it starts be ready to pump a squirt of fuel erry 3 seconds . If it stays running doing this . Then you're carb idle circuit is clogged . Carb will be coming off fo cleaning. Kevin or dellorto or some brand of carb clearly marked ?

Is the idle properly adjusted? The ringing is normal for a 2-stroke.

If This Engine Has Rubber Boots Between Carb And Intake Port(Head) The Clamps May Be Loose Or The Rubber Boot May Be Cracked Or Permeated( Leaking Air, Lean Condition). Never Use Starting Fluid To Test It Will Wash Oil From The Cylinder Wall. Use WD-40 It Contains A lubricant.

Check to see if something is causing the float in the carburetor to stick, which could be preventing fuel from filling the bowl up.

you will probably need to clean the carb there is a you tube video on how to remove and clean

starting fluid is a thing of the past. dont use it. this car doesnt have a carb, its a throttle body/ electronic fuel injection system. you most likely have a fuel pump or fuel pressure regulator issue. test the fuel pressure, should be anywheres from 35-50 psi

If the plug is firing OK then the Kill switch has no connection with the problem.
The problem seems to be the gas supply. There are three things required to start a gasoline engine. The gas, the spark and the minimum RPM. Two of these are available and the third gas is seemingly missing. So, please check if it is getting the required gas. Since gas is gravity fed in bikes, make sure it is reaching the carb in sufficient quantity.

too much fuel will cause same symptoms, grab a can of car throttlebody cleaner from the parts store, and pinch the fuel line off, and attempt to start till fuel is empty in the bowl of the carb, then spray cleaner in carb with the throttle full open 2 to 3 times close throttle, start, as it attempts to run spray slowley while engine runs, adjusting the flow as you rev engine.this eleminates poss bad gas or carb problems. if it runs fine this way then check gas, and check the carb. (while cleaning use a small wire to clean the tubes inside the carb as well, good luck!