Re: Help! totally confused.
To clear the frame and to be able to use the fat rear tire that comes on the Switchblade, the engine needs to be off-set to the left 9/16" from center. That will allow you to not use a tensioner. There is at least 2" of horizontal adjustment in the rear drop outs which should provide ample chain tension adjustment.
The drawing the OP posted shows that the engine is not only cocked in the frame, which alone will cause chain derailment problems, but is also mounted in the center of the frame at the seat tube.
The Switchblade, like several other chopper style bikes, is a unique frame that requires some special work to achieve a successful and reliable bike. Yes, you can simply throw an engine on one and get it to ride but you'll probably end up with the problems this man is having with his. Just saying.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"