So your buddy calls you up, wants to know if your up for a ride tomorrow, against common sense, you say sure.
When checking your bike over you discover it wont start, at this point you begin to get angry, throw a couple tools across the shop etc. etc.
Well, calm down, it may be a little thing, Im going to give you a small check list to help you out a little.
Well, in order for a engine to run it has to have a few basics.
-fuel
-air
-compression
-spark
If any of these are missing the bike will not run.
So naturally, you should make sure your bike is getting all of these.
Make sure its still getting fuel, how is the bike on fuel? the spout on the pet **** is higher than you think, top it off, see if it fires. If this dosnt solve it, make sure the bike isnt clogged up, run through the fuel system all the way to carb and make sure the fuel is at least reaching the carb. If it is, make sure your jets arent clogged up, lossen up the clamps that hold your air box boot to your carb and your carb to your engine, rotate the carb towards you and pull the bottom of the bowl off. There should be too small bronze hex heads in there, pull them out. Go out side and see if you can see sunlight through them, if you cant, they are clogged up. Blow them out with carb cleaner and reinstall, be careful not to over tighten, the brass will break easily. If your ride fires, have fun
Now if that didnt fix it, move on to your air. Done any work with your filter recently? its possible you left something thats blocking your intake, maybe a piece of card board, get to where you can check it over, if there is remove what ever is in there. If this dosnt fix it, when was the last time you cleaned your air filter? clean it, throw it back in, and try it, she starts, your done
still nothing? check your compression. As a little test, stick the bike in gear and try to push it, it shouldnt move more than a couple inches, if it does this is a problem. If its a 4 stroke it could be vavles or a worn out top end. If its a 2 stroke, most likely a new top end, either way, your gona need to do some engine work.
so if your bike passes that test, move on to your spark, pull the plug, and im sure 4stroke owners are dreading this, but you want to ride dont you? leave the plug wire on, have a friend press it agains your engine, and kick the bike through, there should be a spark at the end of the plug. If there isnt, or its weak, spark is your problem. Clean the plug and see if you can get spark, if not, find a new one and check that, if that dosnt work, back trace your electrical looking for broken wires and power all along the circut.
this is just a brief intro on working on your bike, try these before you worry about anything else, you dont want to buy something only to find out it was something silly now would you