Stored in a warm place with stable temperature the whole winter.
Tank filled two last times last Fall with well preserving small engine gasoline which was used successfully also during earlier storage period of a couple of months.
Air filter cleaned last Summer.
Battery is 2 year "similar as the original HD battery" from an HD shop. Just load tested to be ok. 12.9 V two hours after charging and after a couple of starting trials still 12.6 V. Still also jumpstarted with a car but that did not help either. Changed new spark plugs although the earlier ones were used only for one summer. Gives a visible spark.
Even cleaned the battery terminals and measured the contacts. Connections should be ok. But always the same: after turning ignition on, a small normal sound of a few seconds after which I press start button and the starter rotates well, but nothing else except some smell of gasoline after trying to start the engine a couple of times. Has the alarm system but that seems to disarm normally. And yes, the killer switch is in the run position.
Any hints?

 

Take a look at the crankshaft positioning sensor. They can cause a crank with no start.