Yes - the plug is a tamper preventative device - you cannot accurately adjust the screw without the proper tools - just because the carb is 'factory' does not mean it is suited to the application. What is the brand name of the carb?

 

It's a mikuni. It's the oem carb that came. Long story short the quad needed a small amount of choke to get from idle to about 1/4 power. The rest was fine now after I cleaned it. It starts and runs good but idle it dies.

 

It idled fine prior to cleaning the carb?

 

Yes but needed a small amount of choke. I think I need to remove the screw clean it out and re adjust it

 

If it needed a small amount of enriching by opening the bypass starter circuit, it was because the pilot jet or pilot jet circuit was/is partially plugged or gummed up and the cleaning was incomplete - the screw does not to be adjusted, the carb needs to be cleaned more thoroughly.

 

Doesn't the screw need to be removed in order to properly flush everything out and clean the enrichment circuit

 

No - the pilot circuit is not connected to or part of the enrichment circuit. The only way the pilot circuit gets clogged or dirty is from old fuel turning to varnish, from insufficient air filtration or improper cleaning. I never remove the pilot screw and seldom need to adjust it form it's factory setting unless changes have been made to the intake. I clean carbs with a heated sonic cleaner and the cleaning agent enters the idle circuit removing dirt, varnish and most carbon in a 20 minute bath. I do remove the pilot jet as well as the other fuel circuit control components, but the pilot screw only need to be removed if being replaced. It controls the fuel vapor entering the fuel absent air stream passing by the air control butterfly valve at the idle speed opening of the butterfly plate.

If you need to change the screw or setting, the brass plug must be removed. To remove the plug, use a suitable drill bit to drill a hole large enough to tap threads into or screw a small sheet metal screw into. The trick is to not contact the pilot screw with the drill bit. If you touch the pilot screw with the drill, it will change it's position and you will have to re-calibrate the idle. If you do not touch the pilot screw with the drill bit then when the plug is removed, turn the screw in counting the turns until it is lightly seated. At this point, the tip of the screw may be felt or seen protruding into the venturi slightly. Record the number of turns that the screw was set at to the nearest 1/8 turn, then remove the screw, spring, washer and o-ring. Perform the cleaning operation and reinstall the screw to it's prior setting.

If the screw position is changed by drill or other plug removal contact, then re-calibration will be required. Calibration has to be done using 87 octane non-ethanol unleaded fuel. To re-calibrate the pilot screw setting; first set the screw to the service manual specified 'initial setting' for the model of ATV the carburetor is used on. In the case of the 2005 Sportsman 400, the initial setting is 2 3/4 turns out from lightly seated. At this setting, ride the vehicle for 15 to 20 minutes to bring the engine to normal operating temperature. With a fan blowing air across the engine (and through the radiator if liquid cooled - do not rely on the radiator cooling fan to maintain a stable normal operating temperature - you want to simulate vehicle movement), connect an accurate tachometer and set the idle speed to the desired rpm. Turn the pilot screw in by 1/8 turn increments pausing 3 to 5 seconds between adjustments. When the engine idle speed decreases by 50 rpm, turn the pilot screw out one full turn and this is the final setting of the pilot circuit.

 

Thanks for that. I'll get on it this weekend