Replaced blown head gasket on no.2 cylinder of my 25hp intek twin motor on my riding mower. Now it will only run using starter fluid. Good compression at both cylinders, good spark at both plugs. Only problem before was low compression on no.2 cylinder not sure what could have changed but I also noticed now the exhaust on the no 2 cylinder is hot and on no 1 it is cold like it is not getting fuel or fire to that cylinder. But everything seems fine, good compression, good spark, checked valves and push rods everything OK. Could a sheared flywheel key cause a problem with just one cylinder?

Sounds like the fuel solenoid on bottom of carb.

sounds like the fuel solenoid on bottom of carb.

Thanks DG. You were right. Tested it and found it was not working, sticking from old fuel, just cleaned it with carb. Cleaner and got it working again. Starts and runs now but I have popping while running. Cleaned entire fuel system while working on solenoid, new lines, filter, fresh fuel etc. Any suggestions on popping sound, have not checked flywheel key, however it started and ran before replacing head gasket just low compression on no. 2 cylinder which caused it to die out when I tried mowing with it.

Check your valve clearance,these set a 1/4 inch past top dead center.
Set them at about .005.