I just got this kodiac 400 from my brother it was in working order i was never able to pull start the atv just to hard but now it will not start and when i try to pull start it it is very easy to pull like it has no compression i did not do a compression test but when i remove the spart plug and try to start it it will blow my finger out the way what could be stopping it from starting im getting gas and spark and y is it so easy to pull over now timing chain is not broken

 

Try adjusting the valve clearances. If that doesn't work, do a compression test. Also fit a new plug in case this is the reason for the bike not starting.