Harley cart old school

[neadle]

I can get it to fire and run a little but wont stay running. Cleaned carb and new gas, No change. Put gas in plug and in carb and it runs for a minute. Has a hose under the carb that is blocked off with a bolt. Don't know where it go's. How would I check the crank seals cause when I crank it over it don't seem to have much vacunm at carb when I cover with my hand.