So you own a 2 stroke dirt bike, and it wont start, why? Well before you throw wrenches across the shop, try some of these tips.

If its been sitting for any amount of time, the jets may be clogged, pull the bottom of the bowl, pull out the jets, and squirt them with some carb cleaner till you can blow air through them with your mouth. Make sure the carb is in working order.

Make sure the fuel line isnt cracked, and make sure everything in the carb is as it should be (float height orings in good shape etc) Make sure the air filter is clean, as well as the filter on the end of the fuel valve, you will have to remove the valve from the tank to do this.

Whats your gas mixed at? 32:1 is what is recommended most of the time, make sure your mixture isnt too rich for the actual carb jetting.

Pull out the spark plug, make sure it isnt fouled and has a good strong spark.

Saftey precaution: Dont touch the actual plug itself when your testing spark (aka holding it against a piece of metal with the boot on it while someone kicks the bike over) touch the actual boot itself but not the plug.

If you have the gas mixed right, and the plug is fouled, then your jetting is off, you can either go leaner on the oil, or leaner on the jetting, I recommend the later, as the oil in the fuel is the 2strokes life line, thats all the lubrication it gets.

If you dont have a strong spark, check the electrical system, replace the plug, make sure the plug wire is secure on both ends and that its not frayed or other wise, make sure your getting the correct amount of electricity from the stator. Search for broken wires or bad connections, a voltmeter and a test light will really help here.

If all this checks out, check the compression, your manual should give you a spec for this, check using a compression tester.

It screws into the spark plug hole and gives a reading when you kick it over.

If you dont have one and/or cant get one, you can stick the bike in 1st gear with the plug in, and roll it, if the rear wheel spins in complete rotations or give very little resistance, you most likely have low compression, or you can take the plug out, stick your finger in the plug hole, and have a friend kick the bike over and make a rough guess based off of that, however, it is best to just get a good quality compression tester, they are cheap on ebay.

If you have low compression, its time to most likely replace the rings, and possibly the piston. Dont forget the gaskets.