you can run a long bar....because you can......learn how to run a bit smaller bar first.....you had a million different back cuts....if you wanna learn.....cut that tree down with your 66 and a smaller bar....few men can handle a bar that size....and most are in the business....because you have the power to run a bar that long...and u do.... doesnt mean you should. Im not trying to knock you or say Im better...nobody here will grade you because your a sponsor and your helpful to the guys and gals......I will give u a c-.... good luck