IdahoMtnSpyder
Active member
https://www.spyderlovers.com/forums...ed-Premium-vs-Regular&highlight=guess+premiumI think Idaho Mountain Spyder kept an extensive log over a long time of his experience with difference fuel grades and posted his conclusions here. Maybe he will chime in.
Compression per se does not dictate the need for premium to avoid pre-ignition. Pre-ignition is caused by elements inside the combustion chamber staying so hot they cause the fuel to ignite before the piston is at prescribed position near top dead center. What I figure is the combustion chamber of the Rotax engine is so smoothly crafted there are no sharp features inside the chamber that stay hot enough to cause early combustion.
Regular fuel ignites at a lower temperature than does premium.