Bent frame..Call it customized...
Most simple way to check if frame is bent is string line bike from front rim to back rim both sides..
Then do same from front forks to rear swing arm outer ends.
They are never perfect straight,,,even brand new..
Main thing is make sure wheels are parallel, if there not then it will ride like a 3 legged dog..
if they ar parallel and less than 5mm off center no big deal..
more than 10mm and it will handle like a standard harley belt drive..Yep, there not straight..lol
This simply results in a bike that will push the front on lefts and tuck the front on rights...
We used to get frames bent/straightened over east.
I do not no of a frame jig in perth..