Check for fuel in the line and carb should be wet when choking. Check for intake leak. RechecK timing for TDC on piston and manufactures degrees btdc. Check spark works consistently. After all that send it in for repair or replacement. My big twin was doing the same thing. Had intake leake. Also slipped timing. If ingition is good and has intake leak it could do what your saying when it was running. If timing slipped just beyond range of magnet it will not start but pop on choke then pop on choke off but not run. I fought mine for couple weeks got it repaired and running the after four flights same situation. [&o] Sent in for repair and now have time for my arm/shoulder to heal.[&:]