Snowmobile engine starting problem Help!?

[1979 Scorpion Sting]

The snowmobile is a 1979 Scorpion Sting that I bought at an auction for $25. It is in pretty good condition. It will fire but it wont start. I have new spark plugs. It has good compression and spark. I tried to squirt some gas in the heads but all it does is fire. Sometimes It will run for 3 to 4 seconds and then shut off. I filled up the carburetor with fresh gas. Could somebody help?

[Torque]

there are a number of reasons it is doing that and with out really being there it is kind of hard to determine the problem. but my best bet is if u'v changed the spark plug and it is fireing but not starting the carb. probably needs R&R or rebuilding. with it being that old it is possible that it has not been rebuilt in some time. ur jets can become clogged with trash and the diaphragms can become brittle and sometimes bust.now where i'm at a typical carb rebuild kit will cost u about $13 to $20 if u do it urself. but if u have someone to do it for u it can run $50 to a $100. now there are a lot of small important parts in the carb so if u'v never built one before u might want to have someone do it for u.