I just rebuilt this 03 yz 450 after its been siting for a couple years. Ive been trying to start it but its not going well. I change the plug and getting spark. I believe Im getting fuel bc the I can smell it on the plug. I kick it over a bunch and all I get is a few puffs of smoke and occasionally a backfire. Could I possibly have the timing off? I timed it according to the manual but I was wondering if maybe I could have the timing off and have it firing on a decompression stroke instead of a compression stroke?