Ben what I found on Crofter's 260 was with the stock airfilter on it was slow on picking it's rpm's up and didnot sound good to me , it didnot have that crisp engine sound to it , why cause the stock airfilter will not let enough air in to the motor and to make it even try to run you needed to turn the high speed jet way in to lean the fuel down because of no air , and i could not lean the carb down far enough to get it to lean , i turned the high speed jet in all the way and all that happened is it cut faster, so then i took the filter off , b oy you needed to back those jets out then, it sounds alot better , works alot better
so with the airfilter on you most likely are richer even if you set the rpm's with a tack cause of no air, now that you have modded the filter and it is getting more air , it is leaner and has alot more power so you should get more cuts out of a tank of fuel