I have a 1989 Polaris Trail Boss 250. I rebuild the carburetor twice. I even bought a used one on ebay and tried it and same issue. When I choke it and spray starting fluid in i t will run and race really high. When I turn off the choke it will die almost instantly. It has 125 psi compression, new spark plug, fresh gas pre mixed with oil.

I took off the head and it does not appear to have a gasket between the top head and cylinder. When I crank her over and put my hand over the carb it does not appear to be sucking in any air. Shouldn’t it be sucking air to draw the fuel into the cylinder?