I'm having trouble with my 2003 yz450. A few months ago I went to kick start the bike and I had the kick start lever kick back. The bike didn't start and after the kick back the lever felt like it was stuck. I pulled the crank case off and found that the kick idle gear and gear on the kick axel assembly had both broken a few teeth. I replced both gears put everything back together. The bike started up after a few kicks, ran for a few minutes and then died. After a lot of kicking I have got the bike started a total of three times all with the same result, After a few minutes it dies. I've cleaned the carb but have not checked the valves. A few side notes: after a couple of minutes trying to get the bike started I'll let it sit for a minute of two. when I go to kick again the kick start lever is very hard to kick. after a few tries it becomes easier. I have had a couple of individual soft pops out of the exhaust after kicking for a while. also, when filling the bike back up with oil I added 1.2L. I realized my mistake only after I ran the bike for a few minutes at which point I drained the excess oil. Could I have created and issue by running the bike with too much oil? Any help is much appreciated!