Diagnosing some running conditions.... fuel related

Hey guys, Haven't had a chance to sit down and work on anything to take pics, so I will start with just some written tips related to fuel and air. So as a technician in a shop the most common problem I see with motorcycles that are carbureted goes like this... scenario "hey I just tried to fire up my bike and it spits and sputters and won't run of choke" " Has it been sitting?" "only for a few months, I parked it in October for the winter" (It's now February...) OK well it probably needs a carb clean explanation: fuel turns into varnish over time, It evaporates and what is left is usually is condensed petroleum in the form of oils and the additive put in by the petroleum company where you bought the fuel. This stuff can get real nasty. In most constant velocity carburetors there are 2-3 jet circuits. A pilot jet, which meters fuel at idle when the throttle plate is almost closed. A main jet circuit, which feeds the needle jet/jet needle and usually a few small ports that are revealed as the throttle plate begins to open. And on some carburetors there is a mid range jet, but it is not very common. There is also a small leak jet usually mounted in the bowl, but that is only on carburetors with accelerator pumps on the bowl (for instance, if you have a twin or an inline four usually only one of your carburetors will have an accelerator pump) The most common issue with any bike that has sat for a while is plugged pilot jet(s). A jet is a way to meter fuel so it has a specific opening size. pilot jets on most motorcycles are so small that a single strand of wire or fishing line is the only thing that will fit through them. so they become plugged very easily. usually this can be determined by a few symptoms, 1)Bike is hard to start 2)Bike will not idle unless it is on choke 3)bike coughs and spits under acceleration,and after-fires on deceleration. There used to be chemicals a person could add to the fuel to clean it out. Yamaha used to have one, but I think the EPA made them pull it. (at least in California....) so what you have to do is pull the carburetors, pull the bowls, pull the jets, and run something through them. I usually use a strand from a wire brush like a BBQ brush or something. Don't use the bristles that are wavy they don't work. also, if it won't go, don't force it through. Remember it is a fixed orifice size, and it is made of brass which is very soft. If you try to force something through it you may open up the hole, it will let more fuel through, and your bike will have a rich idle mixture. I also suggest dipping your carburetor. There is a water based carb dip that yamaha makes that is fantastic it is called yamalube carb dip, it is a concentrate, and can be found at mos Yamaha shops, or they can order it

At one of the shops I worked at we would mix 3 bottles with the appropriate amount of water in a 5 gallon bucket. We would put a whole rack of carburetors in it and leave it over night, that stuff is amazing. And it doesen't damage things like rubber or plastic. Then pull it out and rinse it with some warm soapy water like simple green or something, use an air blower and blow through all the passageways, reassemble and voila! Also when cleaning the pilot circuit, you should allways pull the air/fuel screws and blow through that passage way. there will be a spring with a 3mm silver washer and a 3mm oring. when reinstalling the fuel screw it you should stack these items on the screw in this order, spring, then washer, then oring. I see a lot of people mix these up and their bike won't idle right.