Wont start I have a Yamaha 04 125L dirt bike its getting a spark and gas but it wont start i have checked the fuses they are still good i am stumped. I asked a service guy at the dealership and he said if its getting a spark and gas it should start.

Did you try 2 new sparkplugs?

Test the stator those go in them quite a bit

First, you need a good battery. The bike does have electronic ignition. Soak the carbs in denatured alcohol for two hours after removing the float bowls, then clean with spray cleaner. Spray into every large and small hole you can find. Remove the rubber diaphragm from the center of carb prior to cleaning. New diaphragms are $196 each. Check all fuses. Put in new spark plugs, NGK-BP7ES. Clean the air filter. Get a can of spray starter fluid and spray on the air filter. The rubber mounts for the carbs are likely to be a problem once it gets running. It looks like they are still available at Babbitt's, $53 each. If un-carburetored air can get into the joints it will lean the fuel mix and cause uncontrollable high idle.

Before you sink a lot of money into the bike, check for spark. If spark is present, coast the bike down a good sized hill without any spark plugs being installed. Put the bike in 3rd gear as you go downhill then let the clutch out to turn the engine over. Now ( using the clutch lever ), shift through all the gears then neutral. If the bike will not shift properly it likely has a bent shift fork. I can't find any forks avaiable. With a bad tranny I would put it back in the dirt floor building and find a newer bike. Here is a link to Babbitt's. Please rate my answer. Thanks.
www.babbittsonline.com/pages/parts/viewbybrand/default.aspx

To begin with you need a good battery @ 12Volts.
Check if there is spark at the spark plugs.remove one spark plug and earth it (spark plug body) and crank start and observe for the spark.
Check if fuel ( gas ) gets into the combustion chamber.
Try cranking it and thn remove the spark plugs and check if they are wet with gas.
Basically these are two things to check first.
Hope this helps!,
Let me know of the outcome and hope to be of help further..Thks.

Assuming you are using fresh gas. Check to see if gas is coming out of the line, if not blow back up into the tank and if that works there's dirt in the tank. Check the spark by removing the plug and kicking it over with the plug touching the engine, look for spark. If no spark, try a new plug, if still no spark, you have a stator problem. It wouldn't hurt to clean the air filter in any case. Good luck!

check air filter and drain old gas out