Chuck Bunnell (Dart Kart race director at Mid Ohio) used to have plans for the crank up type that many enduro guys still use (I have two just like it). Here is the thread on the old eKarting site with a link to his site where he had plans to build one. Problem is, his domain is for sale and not active any more. So . . . Calling Chuck. Can you make those plans available somewhere again?