need help on why my 1995 600 xcr polaris snowmobile wont start it fires but

[brianstumo50428]

wont keep running? i have a 1995 polaris 600 xcr snowmobile it was starting hard know it wont start on full choke it does fire but wont stay runnning with choke off it wont even fire i did accidently hit kill switch acould nd pulled it over several times but i,m wondering if i fouled out the plugs even thou it does fire any help would be greatly appreciated!!!