I just got the bike two fridays ago i rode it home saturday morning it wouldnt start. So i changed gas and spark plugs it started but know its back to not starting again this weekend im going to clean the carbs to see if its that. But any other thing you guys can think of can you please let me know thank u

 

Having only owned my 2002 cbr F1 for a few months I'm new to these bikes, but what I have learned from my own experience is that they need a really well-charged battery of at least 13.5 volts to get them to start. They will turn over with a lower voltage, but I've found my bike won't start unless the battery is right up on voltage. I only have to press the starter for a millisecond and she's away and running, whereas when I first bought her the motor would spin over and in my opinion was turning fast enough to have been able to run, but no way! Try charging your battery overnight off the bike and see how it goes then. To see if you are getting fuel through to the engine, after turning it over for a few seconds, remove one of the spark plugs and see if the tip is wet. If it is, then fuel supply is ok, but if the plug tip is bone dry, then there is something wrong with the fuel supply. It might sound obvious, but if you have a spark, fuel, good compression and the valve and ignition timing is correct, it has to start! Any one of these things wrong and it won't. Methodically check all of these in order, starting with the fuel, plugs, valve timing and finally ignition timing, first manually to get the static timing right then with a stroboscopic timing light to check for ignition advance. Good luck.

 

What do you hear when you try to start it?
Do you hear the relay "click-click-click" noise? Does the engine turn over?

Does your headlight come one when the key is ON?

I had a similar experience after getting some work done at a Honda place near where I live. Made it "almost" all the way home, bike dies at an intersection. turns out that the battery is dead, but the alternator plug was disconnected. I was lucky i made it home even that far. Simple fix was to re-connect the plug and recharge the battery for a few hours.

More details please.