i own a 2004 yamaha yz250f and last summer i was riding and it just locked up checked the oil and everything else and it was all good. we got it back home and tried to kick it over a couple times and it fired up then locked up again. we then tried adjusting the timing and now it will fire for 2 seconds and die and then locks up if u have any information on wut the problem is and parts i need to replace plz email me @ brian.heinen@yahoo.com THANK YOU!!!!